Meditations 4.28. A black heart is an unmanly heart. When we behave irrationally we act like children or animals. This is why we must examine our impressions so irrational thoughts and beliefs do not get to us. Being an irrational person can have any number of effects on you personally. Although irrational behaviors may satisfy our primal natures, it rarely does any good for our interpersonal relationships or status within our social structures. There is an assumption that as a species, we generally behave rationally. This isn’t always the case. Emotions are the general basis for our externally expressed actions. We are faced with a given stimulus, our endocrine system reacts, and depending on our ability to regulate our emotions, we behave either rationally or irrationally. Since behavior is emotion based, without a degree of control or regulation over our emotions, we can’t behave rationally.