Timaeus

For since God desired to make it resemble most closely that intelligible Creature which is fairest of all and in all ways most perfect, He constructed it as a Living Creature, one and visible, containing within itself all the living creatures which are by nature akin to itself. Are we right, then, in describing the Heaven as one, or would it be more correct to speak of heavens as many or infinite in number? One it must be termed, if it is to be framed after its Pattern. For that which embraces all intelligible Living Creatures could never be second, with another beside it; for if so, there must needs exist yet another Living Creature, which should embrace them both, and of which they two would each be a part; in which case this Universe could no longer be rightly described as modelled on these two, but rather on that third Creature which contains them both. Wherefore, in order that this Creature might resemble the all perfect Living Creature in respect of its uniqueness, for this reason its Maker made neither two Universes nor an infinite number, but there is and will continue to be this one generated Heaven, unique of its kind. Now that which has come into existence must needs be of bodily form, visible and tangible; yet without fire nothing could ever become visible, nor tangible without some solidity, nor solid without earth. Hence, in beginning to construct the body of the All, God was making it of fire and earth. But it is not possible that two things alone should be conjoined without a third; for there must needs be some intermediary bond to connect the two. And the fairest of bonds is that which most perfectly unites into one both itself and the things which it binds together; and to effect this in the fairest manner is the natural property of proportion.