The declaration that the descending souls _become_ rice plants, and so
on, cannot be taken literally for that reason also, that the text
afterwards declares them to _become_ those who perform the act of
generation: 'Whoever the being may be that eats the food and begets
offspring, that being he (i.e. the soul that has descended) becomes.'
Now the meaning of this latter text can only be that the soul enters
into conjunction with the creature which eats the grain; and hence we
have to interpret the previous text, as to the soul's becoming a plant,
in the same way.