Goethe's symmetric colour wheel, 1809
Goethe’s symmetric colour wheel with associated symbolic qualities, 1809

Goethe thought that colour would impact, and be affected by, mood and emotion. He noted a division between ‘plus’ and ‘minus’ colours; yellow and yellow-red were ‘plus’ colours, because (he claimed) they are positive and life-enhancing in character, while blues, purples and blue-greens were ‘minus’ colours, because they (allegedly) evoke anxiety and restlessness.

See here for more interesting ideas on colour