genus, which have differences from belonging to other things, or from subsisting differently, e. g. why is there an echo, or why is there a reflection, and why a rainbow? for all these are the same problem in genus, (for all are reflection,) but they differ in species. Other problems differ from the medium being contained under another medium, as why does the Nile have a greater flow during the fall of the month? because the fall of the month is more winterly: but why is the fall more winterly? because the moon fails, for thus do these subsist towards each other.
Chapter 16
Some one may perhaps doubt concerning cause and that of which it is the cause, whether when the effect is inherent, the cause also is inherent, as if the leaves fall from a tree, or there is an eclipse, will there also be the cause of the eclipse, or of the fall of the leaves? As if the cause of this, is the having broad leaves, but of an eclipse the interposition of the earth, for if this be not so, something else will be the cause of these, and if the cause is present, at the same time the effect will be, thus if the earth be interposed, there is an eclipse, or if a tree have broad leaves, it sheds them. But if this be so, they would be simultaneous, and demonstrated through each other, for let the leaves to fall be A, the having broad leaves B, and a vine C, if then A is present with B, (for whatever has broad leaves sheds them,) but B is present with C, for every vine has broad leaves, A is present with C, and every vine sheds its leaves, but the cause is B,
