The sun seems to pour out everywhere. And it does spread out, but it doesn't spill wastefully. Its spreading is a stretching or extension. That's why sunbeams are called rays - from the word meaning "to stretch out." You can see what a sunbeam really is if you watch sunlight pierce through a small hole into a dark room. It always travels in a straight line. When it hits something solid that air can't pass through, it gets cut off and stopped. But it doesn't slide away or fall down - it just stays right there.
The sun seemeth to be shed abroad. And indeed it is diffused but not effused. For that diffusion of it is a τάσις or an extension. For therefore are the beams of it called ἀκτῖνες from the word ἐκτείνεσθαι to be stretched out and extended. Now what a sunbeam is, thou mayest know if thou observe the light of the sun, when through some narrow hole it pierceth into some room that is dark. For it is always in a direct line. And as by any solid body, that it meets with in the way that is not penetrable by air, it is divided and abrupted, and yet neither slides off, or falls down, but stayeth there nevertheless: