The more serious metaphysical and theological speculation of the rabbis was embodied in the doctrine of the "Creation," and the "Chariot," [Hebrew: m'sha br'shit] and [Hebrew: m'sha mrkba], which in form were commentaries on the early chapters of Genesis and the visions of Ezekiel. They were reserved for the wisest and most learned, for the rabbis had always a fear of introducing the student to philosophy until his knowledge of the law was well established. They held, with Plato, that metaphysical speculation must be the crown of knowledge, and if treated as its foundation, before the necessary discipline had been obtained, it would produce all sorts of wild ideas. Judaism for them was primarily not a philosophical doctrine but a system of life. The Hellenistic school was so far false to their standpoint that it laid stress for the ordinary believer upon the philosophical meaning as well as upon the law. And as events proved, this led to the neglect of the law and the dogmatic establishment of speculative theories as the basis of a new religion. Doubtless the consciousness that the philosophical development led away from Judaism increased the distrust of the later rabbis for such speculation, and made them regard esoteric as a milder term for heretical; but the warning is already given in Ben Sira: "It is not needful for thee to see the secret things."[317] The Talmud, indeed, records certain ideas about the powers of God and His relation to the universe in the names of the great masters; and in these ideas there are striking resemblances to Philo's conceptions. The Word is spoken of as an intermediate agency;[318] the finger of God is really the Word; the angels are sprung from the Words of God: Ben Zoma declared that the whole work of creation was carried out by the Word, as it is written, "And God said."[319] But on the other hand there are passages in which the rabbis oppose the Alexandrian attitude, and point out in its excessive philosophizing a danger to Judaism, so that in the end they exclude it. Rabbi Ishmael, we are told, warned his pupils of the danger of Greek wisdom.[320] Akiba, living at a time when the Jews were fighting for spiritual as well as for physical life against the combined forces of the Greeks and Romans, proposed to ban all the [Hebrew: sfrim hitsonim],[321] and the Gemara argues that among these were included the Apocryphal works which showed Greek influence. Again, Elisha ben Abuya, the arch-heretic, is held up to reproach because he read [Hebrew: sfri minim],[322] under which title Greek Gnostic books are probably implied.