One of the Moons oldest Calendars is the Celtic tree Calendar.
The Celts believed trees were inhabited by Spirits, Many Scholars believe, this is an ancient Druid system, they thought different trees had magical properties.
The Celtic Calendar is based on the moon phase, a lunar calendar of 13 moons, each was sacred to either the feminine Goddess, or the Masculine God.
The term ( knock on wood) came out of the repect for the power of trees.
The Celtic Calendar starts with the full moon closest to the Yule, around December 21, the winter soltice.
Birch or november, a feminine energy, was the inception moon, for protection of children, purifaction and creativity, the Celtic word is Beth.
Rowan or December , a masculine energy, a time for vision, healing and divination, the Celtic word is Luis
Alder-January , a masculine energy, self guidance, spirituality, teaching, wealth, mental powers, the Celtic word is Fearn
Willow-Feburary a feminine energy, a Witches moon, love, healing, fertility and protection
the Celtic word is Saille
Ash or March, a feminine energy, flowing waters, prosperity, the Celtic word is Nuin
Hawthorn or April, is a masculine energy, the coming of summer, fertility, peace, binding and prosperity, the Celtic word is Huatne
Oak or May, a masculine energy, strenght , security, all positive magic, the Celtic word is Duiir
Holly or June, a feminine energy, encirclement, polarity, prophecy, animal protection, the Celtic word is Timne
Hazel or July, a feminine energy, a time for the wise, spirit contact, learning, the Celtic word is Coll
Vine or August, Androgynous, moon of celebration, Blackberries, Blueberries, grapes ,and thistle, they offer, prosperity, protection, spiritual guidance, dream magic, courage and strenght, the Celtic word is Muin
Ivy or September, A masculine energy, the Harvest moon, resilience, healing, exorcism, cooperation, the Celtic word is, Gort
Reed or October, the blood moon, also the harvest moon, hearth and home, truth, love, fertility, and all family matters, the Celtic word is Ngetal
Elder moon, this has no month, as the Celtic Calendar is based on the 13 full moons as a year. a masculine energy, a moon of completeness, exorcism, banishing, healing. The Celtic word is Ruis