speculator = thinker? to extol as = to extol what as?

Context:
Karl Marx in New York Daily Tribune
Articles On China, 1853-1860

Revolution in China and In Europe
June 14, 1853
A most profound yet fantastic speculator on the principles which govern the movements of Humanity was wont to extol as one of the ruling secrets of nature what he called the law of the contact of extremes. The homely proverb that “extremes meet” was, in his view, a grand and potent truth in every sphere of life; an axiom with which the philosopher could as little dispense as the astronomer with the laws of Kepler or the great discovery of Newton.
More:
http://www.marxists.org/archive/marx/works/1853/06/14.htm