If we confine our attention to the bit of experience itself, we have no means of determining whether it is sensory or imaginary.

Only its setting can decide that point.

Here, we have come to another distinction of much the same sort.

That red glow, that bit of experience, taken by itself and abstracted from all other experiences, cannot be called either a sensation or the quality of a thing.

Only its context can give us the right to call it the one or the other.
This ought to become clear when we reflect upon the illustration of the fire.