“Let us take, for example, this piece of wax which has just been taken from the hive; it has not yet lost the sweetness of the honey it contained; it still retains something of the smell of the flowers from which it was gathered; its colour, shape and size, are apparent; it is hard, cold, it is tangible; and it you tap it, it will emit a sound. So, all things by which a body can be known distinctly are to be found together in this one.
But, as I am speaking, it is placed near a flame: what remains of its taste is dispelled, the smell disappear, its colour changes. It loses its shape, it grows bigger, becomes liquid, warms up, one can hardly touch it, and although one taps it, it will no longer make any sound. One must admit that it does remain, and no one can deny it. What, then, was it that I knew in this piece of wax with such distinctness? Certainly it could be nothing of all the things which I perceived by means of the senses, for everything which fell under taste, smell, sight, touch or hearing, it changed, and yet the same wax remains. […] I must therefore agree that I could not even conceive by means of the imagination what this wax is, and that it is my understanding alone that must have conceived it.” Descartes, René. Discourse on Method and The Meditations, translated by F.E.Sutcliffe. Middlesex. Penguin, 1971. Pp.108 -109).