Yellow is the perceived color of sunshine. It is associated with joy, happiness, intellect, and energy.

MARCIA MOSES, Understanding Color

There is a sun, a light that for want of a better word I can only call yellow, pale sulphur yellow, pale golden citron. How lovely yellow is!

Vincent Van Gogh

We find from experience that yellow excites a warm and agreeable impression…. The eye is gladdened, the heart expanded and cheered, a glow seems at once to breathe toward us.

JOHANN WOLFGANG VON GOETHE, Goethe’s Theory of Colours