LVI PHILOSOPHICAL SOCIETY OF WASHINGTON. 
been, and still is, of immense importance in human social develop- 
ment. - 
“Four men,” says the Talmud, “entered Paradise. One beheld 
and died. One beheld and lost his senses. One destroyed the young 
plants. One only entered in peace and came out in peace.” Many 
are the mystic and cabalistic interpretations which have been given 
of this saying; and if for ‘“‘ Paradise” we read the “ world of knowl- 
edge” each of you can no doubt best interpret the parable for him- 
self. Speaking to a body of scientific men, each of whom has, I 
hope, also certain unscientific beliefs, desires, hopes, and longings, I 
will only say: “Be strong and of a good courage.” As scientific 
men, let us try to increase and diffuse knowledge; as men and citi- 
zens, let us try to be useful; and, in each capacity, let us do the 
work that comes to us honestly and thoroughly, and fear not the 
unknown future. ; 
When we examine that wonderful series of wave marks which we 
call the spectrum we find, as we go downwards, that the vibrations 
become slower, the dark bands wider, until at last we reach a point 
where there seems to be no more movement; the blackness is con- 
tinuous, the ray seems dead. Yet within this year Langley has 
found that a very long way lower down the pulsations again appear, 
and form, as it were, another spectrum; they never really ceased, 
but only changed in rhythm, requiring new apparatus or new senses 
to appreciate them. And it may well be that our human life is only 
a kind of lower spectrum, and that, beyond and above the broad black 
band which we call death, there are other modes of impulses—another 
spectrum—which registers the ceaseless beats of waves from the 
great central fountain of force, the heart of the universe, in modes 
of existence of which we can but dimly dream. 
