It is not given to a cylinder to move everywhere by its own motion, nor yet to water nor to fire nor to anything else which is governed by nature or an irrational soul, for the things which check them and stand in the way are many. But intelligence and reason are able to go through everything that opposes them, and in such manner as they are formed by nature and as they choose. Place before thy eyes this facility with which the reason will be carried through all things, as fire upwards, as a stone downwards, as a cylinder down an inclined surface, and seek for nothing further. For all other obstacles either affect the body only, which is a dead thing; or, except for opinion and the yielding of reason itself, they do not crush nor do any harm of any kind; for if they did, he who felt it would immediately become bad.

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