When the Hindu writers refer to the Buddhist doctrine in general terms such as "the Buddhists say" without calling them the Vijñânavâdins or the Yogâcâras and the S'ûnyavâdins, they often refer to the Sarvûstivûdins by which they mean both the Sautrûntikas and the Vaibhû@sikas, ignoring the difference that exists between these two schools. It is well to mention that there is hardly any evidence to prove that the Hindu writers were acquainted with the Theravûda doctrines
as expressed in the Pâli works. The Vaibhâ@sikas and the Sautrântikas have been more or less associated with each other. Thus the _Abhidharmakos'as'âstra_ of Vasubandhu who was a Vaibhâ@sika was commented upon by Yas'omitra who was a Sautrântika. The difference between the Vaibhâ@sikas and the Sautrântikas that attracted the notice of the Hindu writers was this, that the former believed that external objects were directly perceived, whereas the latter believed that the existence of the external objects could only be inferred from our diversified knowledge [Footnote ref 1]. Gu@naratna (fourteenth century A.D.) in his commentary _Tarkarahasyadîpikâ on @Sa@ddars'anasamuccaya_ says that the Vaibhâsika was but another name of the Âryasammitîya school. According to Gu@naratna the Vaibhâ@sikas held that things existed for four moments, the moment of production, the moment of existence, the moment of decay and the moment of annihilation. It has been pointed out in Vastlbandhu's _Abhidharmakos'a_ that the Vaibhâ@sikas believed these to be four kinds of forces which by coming in combination with the permanent essence of an entity produced its impermanent manifestations in life (see Prof. Stcherbatsky's translation of Yas'omitra on _Abhidharmakos'a kârikâ_, V. 25). The self called pudgala also possessed those characteristics. Knowledge was formless and was produced along with its object by the very same conditions (_arthasahabhâsî ekasamâgryadhînah_). The Sautrântikas according to Gu@naratna held that there was no soul but only the five skandhas. These skandhas transmigrated. The past, the future, annihilation, dependence on cause, âkâs'a and pudgala are but names (_sa@mjñâmâtram_), mere assertions (_pratijñâmâtram_), mere limitations (_samv@rtamâtram_) and mere phenomena (_vyavahâramâtram_). By pudgala they meant that which other people called eternal and all pervasive soul. External objects are never directly perceived but are only inferred as existing for explaining the diversity of knowledge. Definite cognitions are valid; all compounded things are momentary (_k@sa@nikâh sarvasa@mskârâh_).