The sun seems to us diffused everywhere, pervasive of all things, yet never exhausted. This diffusion is a sort of extension, and hence the Greek word for rays is thought to be derived. You may observe the nature of a ray if you see it entering through some small hole into a darkened chamber. Its direction is straight; and it is reflected around when it falls upon any solid body, which shuts it off from the air beyond. There it stands and does not slip or fall. Now, such should be the flow and diffusion of the understanding; never exhausted, always extending; not violently or furiously dashing against the obstacles that meet it, nor falling aside, but resting there and illuminating whatever will receive it. That which will not transmit the light does but deprive itself of radiance.