When the knack of producing this astral tube is acquired, it will be found that the visualized tunnel seems to vibrate with a peculiar intensity, and will seem to be composed of a substance far more subtle than air.

It is a force without a mind, "more subtle than electricity, but absolutely devoid of consciousness and with no more feeling than the force which lifts the tides."

Laura, who in certain things is as subtle as musk, most likely understood this and therefore showed herself sogracious.

Of the transition there can be no telling in words, for thoughts are more subtle than words and emotions infinitely vaguer.