Thoughts also have colour. For instance, a loving thought has a yellow colour. A thought charged with anger and hatred is of a dark red colour. A selfish thought has a brown colour. Sages see these colours in the aura of a person and thus come to clearly know his mind and character.
—Sri Swami Sivananda
Andrew Harvard Photography 
Very well said
I was thinking.. yellow and brown seem awfully close to each other 😉