H. P. Grice and G. J. Warnock on the philosophy of perception: sense-datum and thing

It might be, perhaps, that the properties of a sense-datum, like the colour red (and so a sense-datum itself), is posterior in some way to a corresponding property of a material thing (and so to a material thing itself).

A property of a material thing, perhaps, render the property of a sense-datum intelligible by providing a paradigm for it.

But when it comes to the provision of a suitably motivated theory of material things and their properties, the idea of making these definitionally or conceptually explicable in terms of a sense-datum and its properties may not be ruled out by the holding of the afore-mentioned definitional or conceptual priority in the reverse direction.