3 ideas
A reclusive inventor finds a way to concentrate sound vibration into a force strong enough to disintegrate matter at a distance, and demonstrates it on solid objects. The mechanism exists only in his mind, and the story ends with him found dead, his brain liquefied. His discovery died with him.
The stories present spiritual and occult phenomena, such as thought condensed into matter or music seen as color, as forces laboratory science simply hasn't measured yet. They describe these forces in the vocabulary of vibration, ether, and energy. The fantastic becomes plausible by extending real science one step past its known edge, not by breaking natural law.
The closing cosmogony presents the universe as the unfolding of a single underlying force or ether. Matter, life, and mind are successive condensations of that force, and they return to it in recurring cycles. The collection's separate strange forces are framed as local expressions of this one principle, so each experiment amounts to tapping the whole.