  It was, perhaps, originally thought that the five physical substances and the five sensible qualities are directly correlated, each quality residing in one and only one substance, odour just in earth, taste just in water etc. (such a view is reported by Vātsyāyana under NS 3.1.65-6). This may give some insight into the origins of the ‘five physical substances’ theory, but it was realised very early on that it is extremely implausible to maintain that earth, for example, is invisible, or else that its colour is always due to intermixture with fire (Bhaduri 1947: 133). The set of correlations between physical substances and sensible qualities is more complex in the Vaiśeṣika-sūtras and later texts, and is indicated in the following chart: