Philo Judaeus De Aeternitate Mundi 97

[97] And so too in the same manner the different kinds of animals, which it is not easy even to enumerate by reason of their multitude, as long as they survive and flourish vigorously, produce a seed, which is calculated to propagate their species; but when they are dead there is no longer any seed. For it would be absurd for a man when he is alive to employ only the eighth part of his soul, which is called the generative power, for the propagation of a being like himself, but after he is dead to exert the whole of himself for the same purpose; for death can never be more energetic or efficacious than life.