SCIENCE 371 



We know it to be true because we immediately perceive 

 it. It is an evident intuition,* and its test is its own 

 luminous self-evidence its evidence in and by itself. 

 We can never prove to ourselves our own existence, 

 it is a self-evident fact which our intellect directly 

 perceives. Closely connected therewith is our power 

 of memory.f Our continuous existence is therein 

 implied, and the validity of our faculty of memory is 

 also implied in every scientific experiment we perform. 

 It is plain that it would be impossible for us to be 

 certain about any careful observation or any experiment, 

 if we could not place confidence in our memory being 

 able to vouch for the fact that we had observed certain 

 phenomena and what they were. 



By asserting the general trustworthiness of our 

 faculty of memory we do not, of course, mean to 

 deny that mistakes are often made. Nevertheless we 

 are all of us certain as to some past events. Every 

 reader of this book, for example, is absolutely certain 

 that he was doing something else before he began to 

 read it. 



Memory gives us as much certainty concerning some 

 portions of the past as we can have with respect to 

 some portions of the present. If we could not trust our 

 faculty of memory, all science would be, for us, a mere 

 dream. But the veracity of that faculty is a self- 

 evident truth. It can never be proved. There can be 

 no such thing as^-oo/of it, because we cannot argue at 

 all unless we already trust it. 



There is another important fact with respect to 

 memory. It not only tells about our own past, but 

 about various facts with respect to other persons and 



* See ante, p. 261. t See ante, p. 259. 



