The author of the Sarvadarçana-samgraha, placing himself with remarkable mental detachment in the position of an adherent in each case, describes altogether sixteen systems. The six which have not been sketched above, besides being of little importance, are not purely philosophic. Five of these are sectarian, one Vishnuite and four Çivite, all of them being strongly tinctured with Sankhya and Vedanta doctrines. The sixth, the system of Panini, is classed by Madhava among the philosophies, simply because the Indian grammarians accepted the Mimamsa dogma of the eternity of sound, and philosophically developed the Yoga theory of the sphuta, or the imperceptible and eternal element inherent in every word as the vehicle of its sense. CHAPTER XVI SANSKRIT LITERATURE AND THE WEST Want of space makes it impossible for me to give even the briefest account of the numerous and, in many cases, important legal and scientific works written in Sanskrit. But I cannot conclude this survey of Sanskrit literature as an embodiment of Indian culture without sketching rapidly the influence which it has received from and exercised upon the nations of the West. An adequate treatment of this highly interesting theme could only be presented in a special volume. The oldest trace of contact between the Indians and the peoples of the West is to be found in the history of Indian writing, which, as we have already seen (p. 16) was derived from a Semitic source, probably as early as 800 B.C. The Aryans having conquered Hindustan in prehistoric times, began themselves to fall under foreign domination from an early period. The extreme north-west became subject to Persian sway from about 500 to 331 B.C. under the Achæmenid dynasty. Cyrus the First made tributary the Indian tribes of the Gandharas and Açvakas. The old Persian inscriptions of Behistun and Persepolis show that his successor, Darius Hystaspis, ruled over not only the Gandharians, but also the people of the Indus. Herodotus also states that this monarch had subjected the "Northern Indians." At the command of the same Darius, a Greek named Skylax is said to have travelled in India, and to have navigated the Indus in 509 B.C. From his account various Greek writers, among them Herodotus, derived their information about India. In the army which Xerxes led against Greece in 480 B.C. there were divisions of Gandharians and Indians, whose dress and equipment are described by Herodotus. That historian also makes the statement that the satrapy of India furnished the heaviest tribute in the Persian empire, adding that the gold with which it was paid was brought from a desert in the east, where it was dug up by ants larger than foxes.