Lent, in the old Saxon, signifiying the Spring, has been applied to the Spring Fast, or the time of humiliation observed by Christians before the Festival of Easter.
The fast, probably like other Christian observances, is of Jewish origin, corresponding with the preparation of the Jews for the yearly Expiation; their humiliation being forty days before the expiation, and ours is forty days before the expiation of the sins of the world by the death of CHRIST.
From the very first ages of Christianity, it was customary for Christians to set apart some time for mortification and self-denial, in memory of the sufferings of CHRIST, and to prepare for the solemn feast of Easter.
This solemn season is limited to forty days, because the number forty was very anciently appropriated to seasons of repentance and humiliation. This was the number of days during which GOD covered the earth with the deluge (Gen. vii. 4.); the number of years in which the children of Israel did penance in the wilderness (Num. xiv. 34.); the number of days Moses fasted in the mount (Deut. ix. 9.), and Elijah in the wilderness (1 Kings xix. 8.); the Ninevites had this number of days allowed for their repentance (John iii. 4.); and our LORD, when he was pleased to fast in the wilderness, observed the same length of time (Matt. iv. 2.).
This season of humiliation was observed by the primitive Christians with the most rigid strictness. No marriages were allowed. Their festivals were transferred from the ordinary week days to Sunday or Saturday; which last day, among the eastern Christians, was a festival like Sunday. Except on these two days, the Eucharist was not consecrated during Lent; that being an act more suitable to Festivals than Fasts. The primitive Christians, during this season, exhibited every external mark of deep penitence and sorrow, particularly abstinence and fasting. They extended the fasting on every day in Lent beyond the hour of three in the afternoon, at which time other fasts ended, to the evening.
[Excerpt from John Henry Hobart, A Companion for the Book of Common Prayer, Containing an Explanation of the Service, 85-86. 1859.]