In the early 1880's, A.P. Sinnett corresponded with the Mahatmas Koot Hoomi and Morya. In these letters, the Masters gave Sinnett the basic ideas of Theosophy on the Constitution of Man; the Planetary Chain; the World Periods; Life after death in Devachan and Kama Loka; the Progress of Humanity; Buddha; and Nirvana.
In 1883 Mr. Sinnett wrote Esoteric Budhism based on his understanding of these teachings. This classic was the first simple exposition of Theosophy in modern times.