Upon what grounds this pretension is founded must now be the subject of our enquiry.
The fundamental principle of that philosophy is the opinion concerning colours, sounds, tastes, smells, heat and cold; which it asserts to be nothing but impressions in the mind, derived from the operation of external objects, and without any resemblance to the qualities of the objects.

Upon examination, I find only one of the reasons commonly produced for this opinion to be satisfactory, viz.

that derived from the variations of those impressions, even while the external object, to all appearance, continues the same.

These variations depend upon several circumstances.

Upon the different situations of our health: A man in a malady feels a disagreeable taste in meats, which before pleased him the most.