XX-THE WORSHIP OF THE OAK. PART 1. THE DIFFUSION OF THE OAK IN EUROPE, Jupiter the god of the oak, the sky, and thunder, Of these attributes the oak is probably primary and the sky and thunder secondary, Europe covered with oak forests in prehistoric times, Remains of oaks found in peat-bogs, Ancient lake dwellings built on oaken piles, Evidence of classical writers as to oak forests in antiquity, Oak-woods in modern Europe. PART 2. THE ARYAN GOD OF THE OAK AND THE THUNDER. Aryan worship of the oak and of the god of the oak, Zeus as the god of the oak, the thunder, and the rain in ancient Greece, Jupiter as the god of the oak, the thunder, and the rain in ancient Italy, Celtic worship of the oak, Donar and Thor the Teutonic gods of the oak and thunder, Perun the god of the oak and thunder among the Slavs, Perkunas the god of the oak and thunder among the Lithuanians, Taara the god of the oak and thunder among the Esthonians, Parjanya, the old Indian god of thunder, rain, and fertility, Gods of thunder and rain in America, Africa, and the Caucasus, Traces of the worship of the oak in modern Europe, In the great European god of the oak, the thunder, add the rain, the original element seems to have been the oak.