What we can imagine as plausible is a narrow band in the middle of a much broader spectrum of what is actually possible. [O]ur eyes are built to cope with a narrow band of electromagnetic frequencies. [W]e can't see the rays outside the narrow light band, but we can do calculations about them, and we can build instruments to detect them. In the same way, we know that the scales of size and time extend in both directions far outside the realm of what we can visualize. Our minds can't cope with the large distances that astronomy deals in or with the small distances that atomic physics deals in, but we can represent those distances in mathematical symbols. Our minds can't imagine a time span as short as a picosecond, but we can do calculations about picoseconds, and we can build computers that can complete calculations within picoseconds. Our minds can't imagine a timespan as long as a million years, let alone the thousands of millions of years that geologists routinely compute. Just as our eyes can see only that narrow band of electromagnetic frequencies that natural selection equipped our ancestors to see, so our brains are built to cope with narrow bands of sizes and times. Presumably there was no need for our ancestors to cope with sizes and times outside the narrow range of everyday practicality, so our brains never evolved the capacity to imagine them. It is probably significant that our own body size of a few feet is roughly in the middle of the range of sizes we can imagine. And our own lifetime of a few decades is roughly in the middle of the range of times we can imagine.
Study, along the lines which the theologies have mapped, will never lead us to discovery of the fundamental facts of our existence. That goal must be attained by means of exact science and can only be achieved by such means. The fact that man, for ages, has superstitiously believed in what he calls a God does not prove at all that his theory has been right. There have been many gods – all makeshifts, born of inability to fathom the deep fundamental truth. There must be something at the bottom of existence, and man, in ignorance, being unable to discover what it is through reason, because his reason has been so imperfect, undeveloped, has used, instead, imagination, and created figments, of one kind or another, which, according to the country he was born in, the suggestions of his environment, satisfied him for the time being. Not one of all the gods of all the various theologies has ever really been proved. We accept no ordinary scientific fact without the final proof; why should we, then, be satisfied in this most mighty of all matters, with a mere theory?Destruction of false theories will not decrease the sum of human happiness in future, any more than it has in the past... The days of miracles have passed. I do not believe, of course, that there was ever any day of actual miracles. I cannot understand that there were ever any miracles at all. My guide must be my reason, and at thought of miracles my reason is rebellious. Personally, I do not believe that Christ laid claim to doing miracles, or asserted that he had miraculous power...Our intelligence is the aggregate intelligence of the cells which make us up. There is no soul, distinct from mind, and what we speak of as the mind is just the aggregate intelligence of cells. It is fallacious to declare that we have souls apart from animal intelligence, apart from brains. It is the brain that keeps us going. There is nothing beyond that.Life goes on endlessly, but no more in human beings than in other animals, or, for that matter, than in vegetables. Life, collectively, must be immortal, human beings, individually, cannot be, as I see it, for they are not the individuals – they are mere aggregates of cells.There is no supernatural. We are continually learning new things. There are powers within us which have not yet been developed and they will develop. We shall learn things of ourselves, which will be full of wonders, but none of them will be beyond the natural.]