Read the following excerpt from Ball's chapter on Ptolemy in Great Astronomers. Imagine a fixed arm to extend from the earth to the sun, as shown in the accompanying figure, then this arm will move round uniformly, in consequence of the sun's movement. At a point P on this arm let a small circle be described. Venus is supposed to revolve uniformly in this small circle, while the circle itself is carried round continuously by the movement of the sun. In this way it was possible to account for the chief peculiarities in the movement of Venus. It will be seen that, in consequence of the revolution around P, the spectator on the earth will sometimes see Venus on one side of the sun, and sometimes on the other side, so that the planet always remains in the sun's vicinity. By properly proportioning the movements, this little contrivance simulated the transitions from the morning star to the evening star.

Now, evaluate the image that accompanied that text.

Compare the information in the excerpt to the diagram. What information from each helps the reader to understand Ptolemy’s theory of how planets move? How do the excerpt and diagram complement one another?