the sky is blue

the sky is blue,
the grass is green.
these are the two sentences I tell myself everyday literally it's become like a quote to me. Why was the sky even blue in the first place ? why was the grass green ? it doesn't make sense at all. wanna know why ? well I have no clear definition but according to many people, the colour blue relieves stress :) And I'm sure God's idea was so when we look at the sky, hopefully our stress and pressure and every negative thought that roams our mind will go away.