The Riddle of the Universe at the close of the nineteenth century

Ernst Heinrich Philipp August Haeckel (February 16, 1834 – August 9, 1919) was a German naturalist, zoologist, biologist, physician, philosopher, professor, and artist. He discovered, described and named thousands of species, coined many terms in biology such as "ecology", "phylogeny, "anthropogeny". He was popularizer of Charles Darwin's theory on German.
"The Riddle of the Universe" (German: "Die Welträthsel, also spelled Die Welträtsel") was written by Ernst Haeckel in 1895-1899, and translated into English by Joseph McCabe as "The Riddle of the Universe at the Close of the Nineteenth Century" in 1900. Let's read the important work of science!