I and others have argued that Paul's use of a seed as an analogy for the resurrection is evidence that Paul believed that the body that was buried was in contiuity to some extent with the body that was resurrected. Alan Segal, guest blogging at The Busybody, has argued just the opposite. While conceding that Paul elsewhere indicates his belief in continuity between the buried and resurrected bodies, Segal argues that the seed analogy indicates a lack of continuity:
The metaphor of the grain of wheat suggests two bodies because the ancient world thought that the seed disappeared and was reborn. Other parts of the passage suggest a single body transformed.
When asked for his source for the assertion about ancient beliefs on the seed, Segal could not remember any. Although I cannot refute what is not presented, the sources of which I am aware indicate it is unlikely that everyone in the ancient world knew that the seed "disappeared," thus rendering the resurrection of a dead body inconceivable. Indeed, many ancient writers other than Paul clearly used the seed analogy to describe the resurrection of the dead body.
There are two passages of interest from the ancient Jewish authors, whose commitment to continuity between the old and new bodies is firmly established. The first is, "If a kernel of wheat is buried naked and will sprout forth in many robes, how much more so the righteous." b. Sanh. 90b. I have explained elsewhere why the reference to “robes” probably indicates a belief in a glorified resurrected body. But even if the meaning is more literal, obviously rabbinic Jews saw the seed analogy as a preferred analogy to describe bodily resurrection. The second is, “All the dead will rise at the resurrection of the dead, dressed in their shrouds. Know that that this is the case. Come and see from (the analogy) of the one who plants (seed) in the earth. He plants naked (seeds) and they arise covered with many coverings; and the people who descend into the earth dressed (with their garments); will they not rise up dressed (in their garments)?” Pirke de Rabbi Eliezer, Section 33.
There are also early Christian sources that use the seed analogy to refer to the resurrection of the body. One is Origen, who states that the “power which exists in a grain of wheat refashions and restores the grain, after its corruption and death, into a body with stalk and ear. On First Principles, 2.10.3. More to the point, however, are some of the earliest Christian references. The author of 1 Clement and Tertullian refer to the seed “rotting away” and “dissolving,” but this does not count against continuity between old and new. (1 Clement 24; Apology 48). These authors clearly affirm continuity by the miraculous power of God to restore the body even from its remaining dust. For when something dissolves and rots away, it does not cease to exist entirely (nor does it "disappear"), but is reduced to dust or ash. But God made man from dust once and according to these ancient Jews and Christians, will do so again if need be at the resurrection. Remember in Genesis that Man is described, "dust you are, and to dust you will return." Gen. 3:19. As described by a Jewish source:
All the bodies crumble into the dust of the earth until nothing remains of the body except a spoonful of earthly matter. In the future life when the Holy One, blessed be He, calls to the earth to return all the bodies deposited with it, that which had become mixed with the dust of the earth, like the yeast which is mixed with dough, improves and increases and it raises up all the body. When the Holy One, blessed be He, calls to the earth to return all the bodies deposited with it, that which has become mixed with the dust of the earth improves and increases and raises up all the body without water.
Pirke de Rabbi Eliezer, Section 34.
A later Christian author also puts it well, mixing the seed analogy with an emphasis on the restoration of the destroyed earthly body:
Some may wonder how decayed bodies can become sound again, scattered members brought together, and destroyed parts restored. Yet no one seems to wonder how seeds softened and broken by the dampness and weight of the earth grow and become green again. Such seeds, of course, are rotted and dissolved by contact with the earth. But when the generative moisture of the soil imparts life to the buried and hidden seeds by a kind of life-giving heat, they receive the animating force of the growing plant. Then gradually, nature raises from stalk the tender life called the growing ear, and, like a careful mother, wraps it in a sheath as a protection against its being nipped at this immature stage by the frost or scorched by the sun when the kernels are emerging, as it were, from early infancy.
Ambrose, On His Brother Satyrus, 2.55.
Other New Testament verses show that early Christians used the seed analogy to emphasize continuity with transformation, such as growth. Matthew 13:31-32 uses the mustard seed as an analogy for the Kingdom, emphasizing its size when “it is full grown.” See the similar usage in Mark 4:26-29. In another parable, the Kingdom is compared to the seed that falls in various types of ground, where it is referred to as having “sprang up” and “grew up.” Mark 4:3-7. These references envision a seed as growing or sprouting, with no emphasis on discontiniuity.
All in all, the fact that so many ancient Jews and Christians unquestionably used the seed analogy to describe the resurrection of the dead body renders it probable that Paul did so as well. I would be interested in seeing references to the seed "disappearing," but have found none in ancient Jewish and Christian sources. There are many references to the seed "rotting away" or "dissolving," but those same references attest to the resurrection of the dead body by God's miraculous power. Uses of the seed analogy in other contexts by Matthew and Mark also emphasize continuity with transformation, rather than cessation and new creation.