light vs darkness

* * * * * _4 October, morning._--Once again during the night I was wakened by Mina. This time we had all had a good sleep, for the grey of the coming dawn was making the windows into sharp oblongs, and the gas flame was like a speck rather than a disc of light...

I walked and, I believe, descended, but I presently found a great alteration in my sensations. Before, dark and opaque bodies had surrounded me, impervious to my touch or sight; but I now found that I could wander on at liberty, with no obstacles which I could...