Ackrill’s Problem is a tension between Aristotle’s alleged view that the matter of a living being is a body that is essentially ensouled, and his view that the matter of a substance preexists its generation. Most interpreters solve the tension by claiming that the subject of substantial generation is not the organic body of the living being, but its non-organic matter. I defend a different solution by showing that the embryological theory ofOn the Generation of Animalsimplies that the organic body (...) of a living being already exists before acquiring the soul in actuality. (shrink)