A rigid mind is that which grasps the dogmas and irrational beliefs, that is not willing to change its opinion nor is able to look for distinct solutions to its problems. For Walter Riso, this rigidness not only favors intolerance, prejudice and discrimination, but it also produces twisted psychology in people. On the opposite side of this is the liquid mind, which accepts everything in a passive manner, your own opinions fall by the wayside, accommodating any situation, even though it goes against your interests. Facing these two attitudes, the author proposes a third alternative; the flexible mind, which allows you to live a more creative, healthier and happier life. It is a critical and open reason that recognizes change and is capable of adapting without renouncing your nature.