Lecture: On the Heaven (de Caelo)

Essays: choose topic: question or passage
            read carefully and do not avoid problems
            web good for initial bibliography search
                        follow up through web of footnotes
            8-10 pages of insightful argument in elegant, simple, and technically perfect prose

A. Method: partly demonstration; partly thesis
                        confirmed by experience and tradition

B. Theorems of the Universe

i. body in three dimensions: three simple motions oriented to a center point
            corresponding natural and unnatural motions
                        the heavy and the light
            circular motion has no contrary, is indestructible
                        has its own body (first body)

ii. no infinite body
            neither the first body: no infinite speed
nor the other bodies (no infinite weight or levity)
            change among infinites impossible

iii. no multiple worlds
            only one center
            one form – many matters: but even in individuals we can make the distinction
            no space or time outside
            spheres are alive
           
iv. world is ungenerated (it was already proved eternal)
            Plato Timaeus
            never seen change in the stars

C. ii.13 and 14 (essay topic?)

i. Ionian flat earth; Pythagorean sphere

ii. earth is at rest in the center: would have to be constrained motion
                                                constrained motion cannot be eternal
also parallax 

iii. it is spherical: jostling of heavy earth
different stars at different latitudes
                        shape of the lunar eclipse
                        400,000 stades circumference (50,000 miles)