Insects are guided by their instincts. The actions of mammals, on the other hand, are born out of a combination of instincts, sentiments, and a certain level of rationality. In humans, a broader range of expression from the basic to the sublime is available. This gives us greater scope for expressing both destructive and constructive behavior. It soars above the instinctual and mental laws of cause and effect.
Sentiments play a large part in human life.
In the subtle anatomy of yoga, there are intricate maps of these various sentiments or vrittis , located in clusters around the various cakras, or subtle energy centers. These vrittis, which in essence are part of the mind, and thus also the brain, effect the subsidiary glands, which are substations between the brain, the nerves and the body. When driven by sentiments such as anger, jealousy, hatred, etc., we create suffering, both for ourselves and others. Many modern health and integral psycho-therapies are, in effect, attempting to accomplish the same thing. Rationality is one of humanity s greatest assets.