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Persons, in this manner co-existing, are called contemporaries: such as Socrates and Alcibiades; Virgil and Horace; Shakspeare and Johnson.
A second mode of co-existence is founded in nature and essence, where two things necessarily reciprocate in consequence of their existing, while neither of them, at the same time, is the cause of existence to the other."
It is in this sense that double and half are together or at once, for they reciprocate; if there be double, there must be half; and if half, there must be double. They are also neither of them the cause why the other exists. Double is no more the cause of half, than half is of double. This last condition is requisite, because if either of the two were essentially and truly a cause to the other, it would pass, by virtue of its causality, from co-existence to priority.
There is a third mode of co-existence, seen in different species of the same genus, when, upon dividing the genus, we view them arranged together, contra-distinguished one to another.
It is thus the genus triangle, being divided into equilateral, equicrural, and scalene, no one of these species appears to be by nature prior, but all of them to exist at once in a state of contradistinction. The same may be said of the three animal species, the aerial, aquatic, and terrestrial, when we divide, after the same manner, the genus animal."
And thus are the modes of co-existence, or together, either the temporal, the essential, or the specific.
And here, should any one object to these distinctions, as either too trivial or too scholastic for the purposes of a polite writer; we answer, that we no more wish an author to mention them, when not professedly his subject, than we would have him dissert, without a cause, upon nouns, pronouns, and the principles of grammar. All we hope from these elementary doctrines, is to see them in their effects; to see them in the accuracy of the composition, both as to reasoning and language. It is thus a grazier, when he turns his oxen into some rich and fertile pasture, never wishes to inspect what food they have devoured, but to see a fair and ample bulk, the effect of food well digested. Besides, when sophists assail us, and either exhibit one thing for another, or two things for one and the same; to what surer weapon can we recur for defence, than to that of precise and well-established distinction?i
e Thus expressed by Aristotle: púoel dè ἅμα, ὅσα ἀντιστρέφει μὲν κατὰ τὴν τοῦ εἶναι ἀκολούθησιν, μηδαμῶς δὲ αἴτιον θάτε· ρον θατέρῳ τοῦ εἶναι. Præd. p. 54. edit. Sylb.
By referring to the chapter on Relatives, it is easy to perceive, whence this speculation arises; for in that chapter the same example is alleged as here, by way of illustration of the same doctrine. See before, p. 316.
f See before, p. 357, 8.
Thus expressed by Aristotle: Kai Tà ἐκ τοῦ αὐτοῦ γένους ἀντιδιηρημένα ἀλλή λοις ἅμα τῇ φύσει λέγεται. Ibid. 55.
Η Αντιδιηρῆσθαι δὲ λέγεται ἀλλήλοις τὰ κατὰ τὴν αὐτὴν διαίρεσιν οἷον τὸ Tvòv tŵ teĠŵ kal т èvúdpw. Ibid. 55.
iLearning and science, or rather learned and scientific terms, when introduced out of season, become what we call pedantry.
There remains to be treated the theory of motion; in which, without attempting to impeach or contradict any modern speculations, we shall inquire, what was the opinion of the ancients concerning it; in what manner they attempted to catch its fugitive nature; and how they divided it by its effects into its subordinate species.
But this is a theory demanding a separate chapter, where those, who question the doctrines, may perhaps amuse their curiosity, while they peruse an attempt to exhibit the sentiments of antiquity upon so singular a subject; a subject, in its existence so obvious, in its real character so abstruse.
CONCERNING MOTION PHYSICAL. ITS VARIOUS SPECIES DEDUCED AND ILLUSTRATED-BLEND THEMSELVES WITH EACH OTHER, AND WHY— CONTRARIETY, OPPOSITION, REST. MOTION PHYSICAL-AN OBJECT OF ALL THE SENSES. COMMON OBJECTS OF SENSATION, HOW MANY. MOTION, A THING NOT SIMPLE, BUT COMPLICATED WITH MANY OTHER THINGS ITS DEFINITION OR DESCRIPTION TAKEN FROM THE PERIPATETICS-THE ACCOUNTS GIVEN OF IT BY PYTHAGORAS AND PLATO ANALOGOUS TO THAT OF ARISTOTLE, AND WHY.
ALL motion is either physical, or not physical. As by motion physical, I mean that which is obvious to the senses; so by motion not physical, I mean that which, by being the object of no sense, (as, for example, the succession of our thoughts and volitions,) is the subject of after-contemplation, and knowable not to the sensitive, but to the rational faculty.
This, therefore, will be the plan of our following inquiry.
In the present chapter, we shall consider motion merely physical, both in its several distinct species, and in its general or common character.
In the next chapter, we shall inquire whether there be other motion besides; and if such may be found, we shall then examine how far it is distinguished from the physical, and how far it is connected.
First, therefore, for the first.*
As the most obvious of all motions is the motion of body, so
The subject may have merit, the terms be precise, and yet, notwithstanding, the speaker be a pedant, if he talk without regard either to place or time.
The following story may perhaps illustrate this assertion: "A learned doctor at Paris was once purchasing a pair of stockings, but unfortunately could find none that were either strong enough, or thick
enough. 'Give me,' says he to the hosier, stockings of matter continuous, not of matter discrete."" Menagiana, tom. ii. P. 64.
k In the order of nature, the genus precedes its several species; but in the order of human perception, the several species precede their genus, which last is the order adopted here. See Hermes, p. 119.
the most obvious motion of body is that by which it changes from place to place,' itself remaining, or at least supposed to remain, both in one place and the other, precisely the same. It is thus a bowl moves over a plane; a bird through the air; a planet round the sun. This motion is properly motion local; or, if we choose a single name, we may call it passage or transition. Its peculiar character, as opposed to any other motion, is to affect no attribute of body, but merely that of local site.
Coeruleo per summa levis volat æquora curru,
Sternitur æquor aquis; fugiunt vasto æthere nimbi.
Æn. v. 819.
Here the chariot flies, the waves subside, the clouds disperse, all is in local motion.
There are other motions, which affect the more inherent attributes. Thus, when a lump of clay is moulded from a cube into a sphere, there is motion more than local; for there is the acquisition of a new figure. The same happens, when a man from hot becomes cold, from ruddy becomes pale. Motion of this species has respect to the genus of quality, and (if I may be permitted to coin a word) may be called aliation.m
If thou be'st he! but O! how fall'n, how chang'd
Par. Lost, i. 84.
Here we behold qualities that are changed, a scene of aliation. Another species of motion is seen in addition and detraction; as when we either add, or take away a gnomon from a square. Here is no aliation, or change of quality, (for the figure, as a square, remains the same in either case,) but the effect of such motion is a change only in the quantity, as the square becomes either smaller or larger. When quantity is enlarged, we call the motion augmentation; when it is lessened, we call it diminu
Behold a wonder: they, but now who seem'd
Here we behold diminution.
Par. Lost, i. 777.
Parva metu primo; mox sese attollit in auras,
Æn. iv. 176.
Here we behold augmentation.
All these motions have this in common, that they are changes or roads from one attribute to another, while the substance re
1 Called therefore in Greek, ή κατὰ τόσ πоν μeтaßоλǹ, and sometimes by a single word, popd. See Arist. Prædic. p. 55. edit. Sylb. and Ammon. in Loc. p. 171. B. m'AAλolwois, in barbarous Latin, alleratio. Vid. Arist. ut supra. " See p. 300.
0 66 Augmentation," atenσis: "diminution," μelwois. Vid. Arist. ut sup.
P See chap. ix. where the species of quantity are enumerated.
4 Οὐ κατηγορίαι εἰσὶν, ἀλλ ̓ ὁδὸς εἰς τὰς Kаτηуорías: "They (that is, these several species of motion) are not predicaments,
mains the same, both in essence and in name. Thus the planet Jupiter, which was a year ago in such a part of the heavens, and is at present in another, though his attributes of place are changed, is yet both in essence and in name still the same planet. By parity of reason, it is the same individual man, who, by change in quantity, from fleshy becomes emaciated.'
But there are other motions, which in their effects go further. Thus, when the substance of a man becomes not only pallid and emaciated, but its living principle is detached from that which it enlivens, putrefaction and dissolution of the body ensue, and it is no longer a change within the substance, but the very substance is lost both in essence and in name. Such motion is called corruption, dissolution, or dying. On the contrary, when the seed of any species, whether animal or vegetable, by evolution, accretion, or other latent process of nature, produces a certain being, which had no existence before; it is a change, like the former, that goes not merely to attributes, but by a more efficacious operation to the very substance itself. Such motion is called generation or birth.
The following difference subsists between these two latter species and the former; the former are no more than roads to different modes of being; the latter lead to being itself, and to its opposite, non-being.
However separate and distinct these species of motion may
but a road to the predicaments.” Ammon. in Præd. 171.
Speaking of these species of motion, Ammonius says, Kiveîodai † karà Toσdv, ἢ κατὰ ποιὸν, κατὰ τόπον, φυλάττοντα Tò ¿§ àρxñs ovσides eldos: "That things are moved and changed either in quantity, or in quality, or in place, still preserving [during these motions] their original essential form." Ammon. in Præd. P. 172.
Here we find the phrase eldos ovoides, commonly called substantial form, but which we choose (as thinking it more accurate) to translate "essential." To explain: Let us, for example, call sphericality (if we may employ such a word) the essential form to a bowl. Every one will admit that the bowl may undergo many changes ; may become white from black, hot from cold ; and (by a more easy change than these) it may roll from one place to another ; and yet notwithstanding it may still continue to be a bowl. But when its sphericality, that is to say, its eldos ovoides, its "essential form," departs, when (supposing its matter to be clay) it is moulded from a sphere into a cube, from that instant the bowl is no more, it has no longer an existence either in essence or in name. See before, p. 275. s See the note immediately preceding. Hence generation is called, óôòs àñò τοῦ πῆ μὴ ὄντος εἰς τὸ πῆ ὂν, τουτέστιν
ἀπὸ τοῦ δυνάμει ὄντος εἰς τὸ ἐνεργείᾳ ὄν: "the road from non-being to being; that is, from being in power to being in act:" corruption or dissolution, on the contrary, is called, ὁδὸς ἀπὸ τοῦ ὄντος εἰς τὸ μὴ ov: "the road from being to non-being." Ammon. in Præd. p. 172.
The particle, prefixed in the quotations to μὴ ὄντος, and τὸ ὂν, is to dis tinguish the non-being and being here mentioned from being and non-being absolute.
means "in a manner," "as it were," "after a sort." See below, p 365. These motions, under the name of changes, (ueraßoλal,) are well explained as follows.
Οταν μὲν οὖν κατὰ τὸ ποσὸν ἢ ἡ μετα βολὴ τῆς ἐναντιώσεως, αὔξησις καὶ φθίσις· ὅταν δὲ κατὰ τόπον, φορά. ὅταν δὲ κατὰ πάθος, καὶ τὸ ποιὸν ἀλλοίωσις· ὅταν δὲ μηδὲν ὑπομένῃ, οὗ θάτερον πάθος ἢ συμβεβηκὸς ὅλως, γένεσις· τὸ δὲ, φθορά : "When therefore the change of the contrary attribute is according to the quantity, it is augmentation or diminution; according to the place, it is local motion; when according to any affection or quality, it is aliation. When nothing remains, of which the new production can be at all considered as an affection, or an attribute, it is then generation; and the contrary, dissolution." Arist. de Gen. et Corr. l. i. c. 4. p. 14. edit. Sylb.
be found, yet being all of the same genus, they naturally blend themselves together.
Thus, though local motion may possibly exist without the rest, yet it is impossible for the rest to exist without local motion. Generation is the assemblage of parts; corruption, the separation; so that here local motion is evident in either case. It is the same in aliation; the same in augmentation and diminution. When fear renders a person pale, such change could not be, did not his blood retreat locally from the surface to within and as for augmentation and its opposite, they are no more than the bringing to, and the carrying off; both which in their very idea imply local motion.
The other species of motion are incidentally blended also. He that increases in bulk, commonly increases with ruddiness ; and he that lessens in bulk, commonly lessens with paleness. There are both in the qualities and the quantities of the particles to be assembled, many changes necessarily previous to generation or birth; and many others, as necessarily previous to corruption or death."
And thus have we established six species of motion, which we denominate physical, because they respect physical subjects. They are to be found in four of the universal genera, or arrangements; one in the genus where, transition; one in quality, aliation; two in quantity, augmentation and diminution; two in substance, generation and corruption.
In all these motions there is opposition or contrariety. Where two species are coupled in one genus, the two species themselves are, in such case, contraries; as generation and corruption, augmentation and diminution. Where the species stands single, as local motion, or aliation, the contrarieties are more numerous, and therefore perhaps not mentioned. In local motion we behold backward and forward, rectilinear and curvilinear, centripetal and centrifugal, &c. In aliation, or change of quality, we behold blackening and whitening; straightening and bending; strengthening and weakening; with many others, to which names are wanting, Lastly, all motion whatever is contrary to
And now perhaps physical motion is.
it may not be amiss to inquire, what Some philosophers have found a short
"See Aristot. Phys. 1. viii. c. 8: where he shews at large, that local motion is necessarily the primary motion, as running through the rest, and essential to them all; and where he likewise explains in what manner the other species of motion necessarily blend themselves with each other. The chapter is too long to be here transcribed. In his tract De Anima, 1. i. c. 3. having spoken of the several species of motion, he adds, that motion infers place, πᾶσαι γὰρ αἱ λεχθεῖσαι κινήσεις ἐν τόπῳ :
"for that all the motions here enumerated are in place."
* See the chapter preceding, p. 355.
! Ἐστὶ δὲ ἁπλῶς τῇ μὲν κινήσει ἠρεμία evάvτiov: “In strictness, the contrary to motion is rest." Arist. Prædic. c. xi. p. 56. edit. Sylb.
The other modes of contrariety are explained in the subsequent part of the chapter here quoted, which in some editions is the fourteenth.