Thoughts are like rainbows they have no substance and no power over you, there is no reason to become its slave.

When a rainbow appears vividly in the sky, you can see its beautiful colors, yet you could not wear as clothing or put it on as an ornament. It arises through the conjunction of various factors, but there is nothing about it that can be grasped. Likewise, thoughts that arise in the mind have no tangible existence or intrinsic solidity. There is no logical reason why thoughts, which have no substance, should have so much power over you, nor is there any reason why you should become their slave.

Dilgo Khyentse Rinpoche