"At the heart of the Stoic doctrine lay a conviction which was...highly favorable to the development of a systematic natural science. For, first and foremost, the Stoics believed in 'determinism'; there was nothing willful about Nature, and everything happened according to law. The secret of human life was to fathom the general character of this universal order and to live in harmony with it. This conviction led certain of the Stoics to elaborate the scientific ideas inherited from their predecessors, but at the same time it reinforced them in beliefs which, to our eyes, appear superstitious. (Their belief in astrological divination...was justified by appealing to the harmony and interaction between celestial and terrestrial events.)"