SMiki55

As is generally known, the Universe, as well as life, describes a wheel. A wheel on whose rim eight magical points are etched, making a complete turn; the annual cycle. These points, lying on the rim in pairs directly opposite each other, include Imbaelk, or Budding; Lammas, or Mellowing; Belleteyn, or Blooming; and Saovine, or Dying. Also marked on the wheel are the two Solstices, the winter one called Midinváerne and Midaëte, for the summer. There are also the two Equinoxes–Birke, in spring, and Velen, in autumn. These dates divide the circle into eight parts–and so in the elven calendar the year is also divided up like that.

When they landed on the beaches in the vicinity of the Yaruga and the Pontar, people brought with them their own calendar, based on the moon, which divided the year into twelve months, giving the farmer's annual working cycle–from the beginning, with the markers in January, until the end, when the frost turns the sod into a hard lump. But although people divided up the year and reckoned dates differently, they accepted the elven wheel and the eight points around its rim. Adopted from the elven calendar, Imbaelk and Lammas, Saovine and Belleteyn, both Solstices and both Equinoxes became important holidays, sacred tides for human folk. They stood out from the other dates as a lone tree stands out in a meadow.

Those dates are also set apart by magic.

Andrzej Sapkowski, The Tower of Swallows