“It seems indeed to be the case that the same thing appears different to different men and different animals and even to one man according to his separate senses and conditions […] since so many different images, or appearances are produced; nevertheless, it can be inferred that there is some general cause underneath in the thing, or object, that is sufficient to produce all these manifestations. And so, however much the effects may not be in conformity with one another, there are still two things which are certain and can be proven true upon examination: one, that there is a single cause in the thing itself, or the object; and two, that there are different dispositions in the receiving faculties. […] Consequently the only task that remains is the investigation of the uniformity of the cause and the dissimilarity of the effects; and if someone should succeed in understanding this, he will be considered to have nothing less than full acquaintance with the nature of the thing and to share in the knowledge of it. For no matter how much it is objected that it cannot be stated definitely from these considerations just what the thing is like according to its nature, but only what it is like in respect to one thing or to another, it may still be said what there is in it which makes it appear to be this in respect to one thing and that in respect to another; and consequently it may be said both to be one thing according to its nature and to be this or that in respect to other things.”
—PIERRE GASSENDI, Syntagma Philosophicum, The Logic, Ch 5: “That some truth can be known by a sign and determined by a criterion”. (Excerpted in Popkin’s Skepticism: An Anthology, p 132)
The Cabbage Farm 