We are told by Maimonides that images or idols were called Tzelamim on account of the power or influence which was supposed to reside in them, rather than on account of their particular figure or form. Townley has opined that the reason for the production of astrological or talismanic images was probably the desire of early peoples to have some representation of the planets during their absence from sight, so that they might at all times be able to worship the planetary body itself or its representative. To accomplish this purpose, the astrologers chose certain colors, metals, stones, trees, etc., to represent certain planets, and constructed the talismans when the planets were in their exaltation and in a happy conjunction with other heavenly bodies. In addition to this, incantations were used in an endeavor to inspire the talisman with the power and influence of the planet for which it stood. Pettigrew says: "The Hebrew word for talisman (magan) signifies a paper or other material, drawn or engraved with the letters composing the sacred name Jehovah, or with other characters, and improperly applied to astrological representations, because, like the letters composing 'The Incomparable Name,' they were supposed to serve as a defence against sickness, lightning, and tempest. It was a common practice with magicians, whenever a plague or other great calamity infested a country, to make a supposed image of the destroyer, either in gold, silver, clay, wax, etc., under a certain configuration of the heavens, and to set it up in some particular place that the evil might be stayed."[76] The Jewish phylacteries must therefore be considered talismans and not amulets. The writings contained in them are portions of the law and are prepared in a prescribed manner. Three different kinds are used: one for the head, another for the arm, and the third is attached to the door-posts. The following is a Hebrew talisman supposed to have considerable power: "It overflowed--he did cast darts--Shadai is all sufficient--his hand is strong, and is the preserver of my life in all its variations."[77] Arnot gives an account of some Scottish talismans not unlike the phylacteries of the Jews, which were for use on the door-posts. "On the old houses still existing in Edinburgh," he says, "there are remains of talismanic or cabalistical characters, which the superstitious of earlier days had caused to be engraven on their fronts. These were generally composed of some text of Scripture, of the name of God, or, perhaps, of an emblematic representation of the resurrection."[78] The connection of astrology, or, as he calls it, "astronomy," and the talisman with medicine is well portrayed by Chaucer in his picture of a good physician of his day. He says: