The eight sacred festivals that mark the turning of the solar year — four solar festivals (the solstices and equinoxes) and four cross-quarter days between them. Together they form the complete rhythm of existence: birth, growth, harvest and rest.
The Wheel of the Year as practised today is primarily a modern pagan construction — systematised in the mid-20th century by Gerald Gardner, Doreen Valiente and Ross Nichols, drawing on Celtic and Germanic seasonal traditions, the Druidic revival and earlier folklore scholarship. The eight-festival structure as a unified whole is largely their creation, though the individual festivals have genuine ancient roots in different cultures.
What the Wheel preserves — whatever its historical complexity — is something genuinely old: the human experience of living in rhythm with the solar year, marking its turning points with fire, feast and ceremony, and finding in the cycle of seasons a mirror for the cycle of inner life. Birth, growth, harvest, rest, death and return.