The primeval man is descended from the monkey, but from which animal does the monkey descend?

Answer

Quite simply we can indeed say that man descended from a primate (or ape). It is not that we are descended from, for example, a chimpanzee, but we have a common ancestor. The last common ancestor of both humans and the great apes is said to have lived about 22 million years ago (Proconsul).
But we continue to classify the ancestors of that ancestor with the apes. And this goes back to about 55 million years ago, because from that period we find the first primates (or apes). Then there lived a primitive monkey that we named Teilhardina. And the ancestors of that Teilhardina? These were small mammals that have slowly but surely adapted to life in the trees.