This tree had, and still has, a critical oracular role and dendromancy is often made by some prophetesses who interpret the Oak's murmur. According to the myth, King Numa consulted the nymph Egeria as an oracle and Egeria is a Driad. Driads are the Oaks' Nymphs: they give life to these trees being also the spirits of these trees. Driads, who live under the oaks' cortex, have the same function of the Genius for a man and the Juno for a woman. They may also leave the tree: for this reason, in the past, it was not possible to cut an oak without the augur's advice who determined if the Driad of that oak had left the tree or not.
Amadriads are the Oaks' deeper spirits: they never leave the tree and they die when their tree dies. In the past people thought that if an oak was in danger Amadriads would have emitted their menacing laments.
The Oak's Authority, as queen among the trees, is the reason why many woods of oaks are dedicated to Juno: the Oaks' authority was also highlighted by the fact that the Roman Emperors had on their heads a crown made of oak leaves consacrated to Jupiter Capitolinus. In Rome the Celius hill was named "the oak woods mountain": here there was a temple consacrated to Jupiter as the Lord of the Oaks and closer there was a small temple consacrated to the Amadriads. The Aedes of Vesta was surrounded by oaks from which the Vestals took the wood necessary for the Sacred Fire. In Preneste the Temple of Fortuna had a sacred area devoted to divination: the oracle's indications were written over oak leaves.
If woods are sacred sites, oak woods are even more sacred: they are the "sanctuaries" by definition and the Temples, with their columns, are a representation of woods and glades.
Traditional Hermetic Simbology
In the past, "longevity", both in material and in meta-physical terms, was the primary oaks' sacred feature: these trees were called "the First Mothers" (as other trees, in the Latin language oak is a female name) and they represented a microcosm also because hosting not only "the Invisibles" but also a large number of sacred animals. In particular the oak is the place where usually the woodpecker lives (a fundamental bird for the auspices). According to the myth, Picus (the Ancient King-Augur) was transformed into a woodpecker by Circe: Picus was married to Canens, Janus' daughter, who, when singing, was able to "make the trees walk". The woodpecker is thus a prophet-bird: a woodpecker brought food to Romolus and Remus in their cavern. Faunus, Picus' and Canens' son, has prophet powers, but, in order to obtain his indications, it is necessary to tie him to an oak.
It's important also to remind that the tree from which the Golden Bough is taken is an Oak (a holm oak) which is defined as the "resurrection tree" because it permits to enter and escape the Inferi. The Golden Bough is of course the "Initiation Light" being the way to prevail over the Darkness. It is also important to provide some very brief information about the role of the oak in the Sacred Science: a spring of Living Water flows from a hollow oak.
Of course these myths, terms and this symbology must be considered within a hermetic perspective.
All this can contribute to understand from the one hand the importance the Oak's role plays, as Sacred Tree, in the Traditional Roman Religion still today: on the other hand it explains the christians' fierceness (in the past but even today) against these trees. This explains for example why many christians monasteries and churches were built inside the woods just to remove the cults practiced in the past to this and other trees: a cult we has the duty to keep alive today.
TO THE MOTHERS-OAKS (invocation)
Man, do not cut
the Acorns' Mother.
Save the Oaks.
It is an ancient adage
for which Oaks are for us
the First Mothers.