Petrography rock was affixed to a microscope slide and then ground so thin that light could be transmitted through mineral grains that otherwise appeared opaque. The position of adjoining grains was not disturbed, thus permitting analysis of rock texture. Thin section petrography became the standard method of rock study. Since textural details contribute greatly to knowledge of the sequence of crystallization of the various mineral constituents in a rock, petrography progressed into petrogenesis and ultimately into petrology. It was in Europe, principally in Germany, that petrography advanced in the last half of the nineteenth century. The macroscopic characters of rocks, those
What Is History? art. Though Carr conceded that historians cannot predict exact events in the future, he argued that historical generalizations can supply information useful to understanding both the present and the future. Carr argued that since scientists are not purely neutral observers, but have a reciprocal relationship with the objects under their study just like historians, that this supported identifying history with the sciences rather than the arts. Likewise, Carr contended that history like science has no moral judgements, which in his opinion supports the identification of history as a science. Carr was well known for his assertions in "What Is History?"