History of chemistry
An important breakthrough in making sense of the list of known chemical elements (as well as in understanding the internal structure of atoms) was Dmitri Mendeleev's development of the first modern periodic table, or the periodic classification of the elements. Mendeleev, a Russian chemist, felt that there was some type of order to the elements and he spent more than thirteen years of his life collecting data and assembling the concept, initially with the idea of resolving some of the disorder in the field for his students. Mendeleev found that, when all the known chemical elements were arranged in order of increasing atomic weight, the resulting table displayed a recurring pattern, or periodicity, of properties within groups of elements. Mendeleev's law allowed him to build up a systematic periodic table of all the 66 elements then known based on atomic mass, which he published in "Principles of Chemistry" in 1869. His first Periodic Table was compiled on the basis of arranging the elements in ascending order of atomic weight and grouping them by similarity of properties.
Emerald Tablet
C.G. Jung identified "The Emerald Tablet" with a table made of green stone which he encountered in the first of a set of his dreams and visions beginning at the end of 1912, and climaxing in his writing "Seven Sermons to the Dead" in 1916. Historians of science, Eric John Holmyard (1891–1959) and Julius Ruska (1867–1949) also studied the tablet in the twentieth century. Because of its longstanding popularity, the "Emerald Tablet" is the only piece of non-Greek Hermetica to attract widespread attention in the West.