Sense-Perceptions

Now, no one denies that our senses, as long as they are normal, are the most trustworthy guides we have, and the facts they gather in for us form the very foundation of the structure of human knowledge. 

But if they mean that all human knowledge is only sense-perception and nothing but that, we deny it. 

If by physical sciences are meant systems of knowledge which are entirely based and built upon sense-perception, and nothing but that, we contend that such a science never existed nor will ever exist. 
Nor will any system of knowledge, built upon sense-perception alone, ever be a science. 

                           - Swami Vivekananda, 
                            found in an unfinished article