Purple and Violet

I always believed the words purple and violet
Referred to the very same hue,
Till somebody said only purple’s the one
That you get when you mix red and blue.

Since violet and red are on opposite ends
Of the visible spectrum of light,
There’s no reddish violet like yellowish green
When a prism divides up the white.

My sources have stated that purple’s not real,
That at most it exists in the mind,
An optic illusion when two separate colors
Are thoroughly, closely combined.

This ties to the difference twixt color and pigment.
I knew that the cones in our eyes
Send signals the brain may not process correctly.
I shouldn’t feel that much surprise.