The third class of evils comprise those which everyone causes to himself by his own action. This is the largest class, and is far more numerous than the second class. It is especially of these evils that all men complain, - only few men are found that do not sin against themselves by this kind of evil. ...This class of evil originates in man's vices, such as excessive desire for eating, drinking, and love; indulgence in these things in undue measure, or in improper manner, or partaking of bad food. This course brings diseases and afflictions upon the body and soul alike.
MaimonidesThere is no difference between the pain of humans and the pain of other living beings, since the love and tenderness of the mother for the young are not produced by reasoning, but by feeling, and this faculty exists not only in humans but in most living beings.
MaimonidesAn ignorant man believes that the whole universe only exists for him: as if nothing else required any consideration. If, therefore, anything happens to him contrary to his expectation, he at once concludes that the whole universe is evil. If, however, he would take into consideration the whole universe, form an idea of it, and comprehend what a small portion he is of the Universe, he will find the truth. There are many ... passages in the books of the prophets expressing the same idea.
Maimonides