Small birds and insects, which feed on very minute insects, need eyes like microscopes to find them; while the eagle and the fish hawk, which soar up till they are almost out of sight, can distinctly see the hare or the herring a mile below them, and so must have eyes like telescopes.

We, too, need to observe minute objects very closely, as when we read fine print, or when a lady threads a fine needle at microscope range; but, if confined to that range, we could not see our friends across the room, or find our way to the next street.

Again, in traveling we need to see objects miles away, and at night we see the stars millions of miles away; but then, if confined to the long range, we should be strangers at home, and never get within a mile of any acquaintance.

Now, how to combine these two powers, of seeing near objects and distant ones with the same eye, is the problem which the Maker of the eye had to solve.
Let us look how man tried to solve it.

A magnifying lens will collect the rays from any distant object, and convey them to a point called the focus.