Sâ@mkhya, Yoga, and Mîmâ@msâ were prior to Buddhism yet they have been
treated after Buddhism and Jainism, because the elaborate works of these
systems which we now possess are later than Buddhism. In my opinion the
Vais'e@sika system is also probably pre-Buddhistic, but it has been
treated later, partly on account of its association with Nyâya, and
partly on account of the fact that all its commentaries are of a much
later date. It seems to me almost certain that enormous quantities of
old philosophical literature have been lost, which if found could have
been of use to us in showing the stages of the early growth of the systems
and their mutual relations. But as they are not available we have to be
satisfied with what remains. The original sources from which I have drawn
my materials have all been indicated in the brief accounts of the
literature of each system which I have put in before beginning the study
of any particular system of thought.

In my interpretations I have always tried to follow the original sources
as accurately as I could. This has sometimes led to old and unfamiliar
modes of expression, but this course seemed to me to be preferable to
the adoption of European modes of thought for the expression of Indian
ideas. But even in spite of this striking similarities to many of the
modern philosophical doctrines and ideas will doubtless be noticed.
This only proves that the human mind follows more or less the same modes
of rational thought. I have never tried to compare any phase of Indian
thought with European, for this is beyond the scope of my present
attempt, but if I may be allowed to express my own conviction, I might
say that many of the philosophical doctrines of European philosophy are
essentially the same as those found in Indian philosophy. The main
difference is often the difference of the point of view from which the
same problems appeared in such a variety of forms in the two countries.
My own view with regard to the net value of Indian philosophical