Many scholars are of opinion that the Sa@mkhya and the Yoga represent the earliest systematic speculations of India. It is also suggested that Buddhism drew much of its inspiration from them. It may be that there is some truth in such a view, but the systematic Sa@mkhya and Yoga treatises as we have them had decidedly been written after Buddhism. Moreover it is well-known to every student of Hindu philosophy that a conflict with the Buddhists has largely stimulated philosophic enquiry in most of the systems of Hindu thought. A knowledge of Buddhism is therefore indispensable for a right understanding of the different systems in their mutual relation and opposition to Buddhism. It seems desirable therefore that I should begin with Buddhism first.