of the oak tree was part of the Proto-Celtic word for 'druid': *derwo-weyd- > *-; however, Proto-Celtic *derwo- (and *dru-) can also be adjectives for 'strong' and 'firm', so Ranko Matasovic interprets that *- may mean 'strong knowledge'. As in other Indo-European faiths, Taranis, being a thunder god, was associated with the oak tree. "Tree" and drus may also be cognate with "Druid," the Celtic priest to whom the oak was sacred. There has even been a study that shows that oaks are more likely to be struck by lightning than any other tree of the same height. In Norse mythology, the oak was sacred to the thunder god, Thor. Thor's Oak was a sacred tree of the Germanic Chatti tribe. In Baltic and Slavic mythology, the oak was the sacred tree of Latvian god Pērkons, Lithuanian Perkūnas, Prussian Perkūns and Slavic Perun, the god of thunder and one of the most important deities. The oak also appears in the Hebrew tradition. In the Bible, the oak tree at Shechem is the site where Jacob buries the foreign gods of his people (Gen. 35:4). Also, Joshua erects a stone under an oak tree as the first covenant of Yahweh, the god of Israel (Josh. 24.25–7). In Isaiah 61, the prophet refers to the Israelites as "Oaks of Righteousness". Absalom's long hair (2 Samuel 18:9) gets caught in an oak tree, and allows Joab to kill him. Veneration of the oak survives in Serbian Orthodox Church tradition. Christmas celebrations include the badnjak, a branch taken from a young and straight oak ceremonially felled early on Christmas Eve morning, similar to a yule log. In recent times, only the branches are collected, brought home, and ceremoniously thrown into a stove or church bonfire. In another tradition, a zapis (lit. "inscription") is an old, isolated oak on a hilltop or promontory, often inscribed with a cross by a parish priest. Reverence for probably originated in pre-Christian times, and they long remained places of public gathering and even of Christian worship where churches were not available. For example, in 1815, at a zapis assembly in Takovo, knez Miloš Obrenović declared the start of the Second Serbian Uprising. Even in modern times, cutting down zapis oaks can result in public outcry, even for projects like road building. History Several oak trees, such as the Royal Oak in Britain, the Charter Oak in the United States,