“Comets are nothing…”

Comets are neither ether, nor gas, nor liquid, nor solid, nor in any way akin to any of the substances found in the celestial bodies, but they are made of an indefinable substance, which appears to have none of the properties of known matter and does not exist outside of the sun beams, which draw them out of nothingness for a minute, before returning them to it. Between the sidereal enigma that is a comet and the stellar systems that constitute the universe, there is a radical separation. They are two isolated modes of existence, two fully distinct categories of matter with no other link than the disorderly action of a near-insane gravity. There is no reason to include the comets in a description of the world. They are nothing, they do nothing, and their only role is that of an enigma.

Auguste Blanqui, Eternity by the Stars: an Astronomical Hypothesis.