na caivambhūtena kāraṇena kvaciddhetoḥ pratibandhaḥ siddhaḥ / nāpi yadātmakaṃ kāryam upalabhyate kāraṇenāvaśyaṃ tadātmanā bhavitavyaṃ
Neither has any invariable connection of the reason with such a cause been established, nor must a cause necessarily be of the same nature as its effect is observed to be.