Divination, or soothsaying, consists in the capacity to read and interpret omens; [1016] and this capacity is, according to the Stoics, partly a natural gift, and partly acquired by art and study. [1017] The natural gift of prophecy is based, as other philosophers had already laid down, [1018] on the relationship of the human soul to God. [1019] Sometimes it manifests itself in sleep, at other times in ecstasy. [1020] A taste for higher revelations will be developed, in proportion as the soul is withdrawn from the world of sense, and from all thought respecting things external. [1021] The actual cause of the prophetic gift was referred to influences coming to the soul partly from God or the universal spirit diffused throughout the world, [1022] and partly from the souls which haunt the air or demons. [1023] External causes, however, contribute to put people in a state of enthusiasm. [1024] Artificial prophesying, or the art of foretelling the future, depends upon observation and guess-work. [1025] One who could survey all causes in their effects on one another would need no observation. Such a one would be able to deduce the whole series of events from the given causes. But God alone is able to do this. Hence men must gather the knowledge of future events from the indications by which their coming is announced. [1026] These indications may be of every variety; and hence all possible forms of foretelling the future were allowed by the Stoics; the inspection of entrails, divination by lightning and other natural phenomena, by the flight of birds, and omens of every kind. [1027] Some idea of the mass of superstition which the Stoics admitted and encouraged may be gathered from the first book of Cicero’s treatise on divination. The explanation of these omens being, however, a matter of skill, individuals in this, as in every other art, may often go wrong in their interpretation. [1028] To make sure against mistakes tradition is partly of use, since it establishes by manifold experiences the meaning of each omen; [1029] and the moral state of the prophet is quite as important for scientifically foretelling the future as for the natural gift of divination. Purity of heart is one of the most essential conditions of prophetic success.