Göğün Küresi

No one of us ascends to the heavens to see the circles and degrees of them, and to revolve them whenever and however one pleases. For those things that are in the past, a man cannot observe them, nor would the age of man suffice to wait for things that are to be; and things that are present, no one can see everything while he is alive. Now in one place it is day, in another night; to one man a star rises, to another it sets, nor is it seen by all people in the same places at the same time. To some, the sphere shows itself straight, and to others obliquely in many ways. For these reasons, it is good and convenient to have an artificial sphere, which can be turned by hand at will, and where the common situation and part can be viewed, and all its degrees and circles can be perceived; at least it is opportune that, by means of such an example, we may easily understand things present, past, and future, and those things which are of the natural sphere of heaven.