“…in the painting I let my own head, in the sense of idea or imagination, work, which isn’t so much the case with studies, where no creative process may take place, but where one obtains food for one’s imagination from reality so that it becomes right.”
Vincent van Gogh, letter to Theo, 28 April 1885
Or put another way: Everything you need to feed your imagination is right in front of you, if you take the time to look.
Shapes, colours, highlights, lowlights and imagination.
Vincent was and still is, a master at all four. He uses all four.
As long as the end result is harmonious and pleasing to the eye, all is well.