How are early Greek and early Indian thought similar? And how do we explain the similarities? These questions can contribute to the current debate about the so-called Axial Age, in which – it is claimed – various civilisations were in the first millenium bce transformed, intellectually and ethically, in ways by which we are still defined.

There is general agreement neither on the dating of the Axial Age nor on which civilisations count as manifestations of it. The focus of this volume is mainly (but not exclusively) on the period from about 800 BCE to Alexander's crossing of the Indus in 326 BCE. In this period we can say that philosophy is to be found in both Greece and India, provided that ‘philosophy’ is defined not by rationality, which is in a sense ubiquitous, but rather by understanding the universe as a systematic whole that lacks any fundamental role for the personal agency of deity. Of course in neither culture was this a majority view. It is certainly not the only possible definition of philosophy, and we might even prefer to call it proto-scientific rather than philosophical. But it defines a phenomenon of considerable intellectual and historical significance, and distinguishes Greece and India (and China) from the other societies that are often regarded as manifesting the Axial transformation: Israel and Iran.

The belief just described as defining ‘philosophy’ is one of many shared by Greece and India in this period. Allen finds a basic pentadic structure in various contexts in both Greek and Indian texts. The development of abstraction, as a prerequisite for philosophy, is traced as early as the Ṛgveda by Jurewicz in the instance of ṛtá – ‘cosmos, order, truth’ – a concept that is then compared with Greek harmonia by Chaturvedi. Other shared ‘philosophical’ beliefs are monism (the belief that everything is in fact a single entity, for which see Seaford, Robbiano, Obryk), and the idea that understanding the (sometimes explicitly incorporeal) inner self or soul (psuchē, ātman) is central to understanding the universe and vital for human well-being.