I'm reading Turgenev's Fathers and Sons, and in it is made reference to the popularity of a philosopher, Condillac, who the abundant notes inform us argued that all knowledge was based on the physical senses.
How did man come to know this wonderful piece of knowledge, I wonder? Was it imparted to him by his physical senses? Perhaps if someone else had told him of this idea, then it could be said to have been indeed transmitted by the senses: the ears if imparted orally, or the eyes if visually on a page. Ultimately, of course, it as an idea has its seat in the invisible dimension of the mind, and not via the physical senses. So the statement that all knowledge is based solely on the physical senses begins and ends in idiotic self-contradiction.