Caption: Portrait of Auguste Comte (1798--1857).
The positivist philosopher Auguste Comte gave the matter composition of stars as an example of something humankind can never know:
Famous last words and hostage to fortune.
Only a couple or so decades after Comte's statement, the elemental composition of stars was being identified from starlight using spectroscopy (see Wikipedia: Star: Observation history; Wikipedia: Fraunhofer lines: Discovery).
It turns out that stars are mainly hydrogen and helium just as our Sun is.
Credit/Permission:
Louis-Jules Etex (1810-1889),
19th century
(uploaded to Wikipedia
by User:P.S. Burton,
2013) /
Public domain.
Image link: Wikipedia.
File: Art file:
auguste_comte.html.