Are All Colors The Same?

I was fortunate to grow up in a household in which color figured prominently, though not on the surface of things.  My father worked for a company that made printing inks.  One of my favorite books was the book of color samples: many copies of a single print each in a different color.  I found it fascinating.  Was it the same picture?  Or had the color become the picture?

In a way this might represent a musical problem.  This Clementi Sonatina is in C.  Would it be the same sonatina if played in D, or F? 

This morning a marvelous student gave me a lesson on why that would be impossible.  The piece derives its entire sense from the intrusion of specific black keys into an otherwise consonant white key environment and boy! do they stick out.

First an F#; soon thereafter E-flat.  The second movement calls for B-flat throughout, and then when you get used to the return to all white keys in the third movement, bingo! a pesky F# returns for a brief appearance.

How much more meaningful these intrusions become, how much more playful, when they are not smothered by theoretical analysis, as they were when I first studied them.

Let the ear respond and green is indeed a different subject matter than, say, yellow.