It's all mutable

What does the word mutable really mean.  
Well, by the dictionary's definition it means 'to change', shifting, but it also means a sense of the fluid, ideas coming and going. 
So that's a good thing, right, because there is always a new approach, a new response, 
a new thought, a new drawing...The street, whatever street you walk down, big or small,
 urban or suburban is full of art.  Someone has felt the need to express themselves.  To say 'I have something to say!' 
Every surface is a canvas.