The Celtic year was not at first regulated by the solstices and equinoxes, but by some method connected with agriculture or with the seasons. Later, the year was a lunar one, and there is some evidence of attempts at synchronising solar and lunar time. But time was mainly measured by the moon, while in all calculations night preceded day.[889] Thus _oidhche Samhain_ was the night preceding Samhain (November 1st), not the following night. The usage survives in our "sennight" and "fortnight." In early times the year had two, possibly three divisions, marking periods in pastoral or agricultural life, but it was afterwards divided into four periods, while the year began with the winter division, opening at Samhain. A twofold, subdivided into a fourfold division is found in Irish texts,[890] and may be tabulated as follows:-- 1st quarter, _Geimredh_, beginning with the _A_. Geimredh festival of _Samhain_, November 1st. (winter half) 2nd quarter, _Earrach_, beginning February 1st (sometimes called _Oimelc_). 3rd quarter, _Samradh_, beginning with the _B_. Samhradh festival of _Beltane_, May 1st (called also (summer half) _Cét-soman_ or _Cét-samain_, 1st day of _Samono-s_; cf. Welsh _Cyntefyn_). 4th quarter, _Foghamhar_, beginning with the festival of _Lugnasadh_, August 1st (sometimes called _Brontroghain_). These divisions began with festivals, and clear traces of three of them occur over the whole Celtic area, but the fourth has now been merged in S. Brigit's day. Beltane and Samhain marked the beginning of the two great divisions, and were perhaps at first movable festivals, according as the signs of summer or winter appeared earlier or later. With the adoption of the Roman calendar some of the festivals were displaced, e.g. in Gaul, where the Calends of January took the place of Samhain, the ritual being also transferred.