 In this case (though not always) one does get far more detail in HA. These references to histories and dissections can be misleading unless one takes into account the differences in the aims, and thus in the organization, of these treatises. In this case, for example, nothing is said in GA about the heart ‘beating and moving as though it were alive’. As we saw, however, GA II stresses that in the development of live-bearing animals, the heart is first to be formed, is ensouled from the start, and is the source of development for all the other parts—a much more ‘theory-laden’ characterization that stresses the heart’s causal role in development. And because of the organizational structure of GA, much of what is said in his discussion of the live-bearing animals (those that are ‘more complete’ when they are born) is assumed to apply to animals that lay eggs (that are ‘less complete’ when born).