Thomas à Kempis (Thomas van Kempen or Thomas Hemerken or Haemerken, litt. "small hammer"; c. 1380 – 25 July 1471) was a canon regular of the late medieval period and the probable author of The Imitation of Christ, which is one of the best known Christian books on devotion. His name means "Thomas of Kempen", his hometown, and in German he is known as Thomas von Kempen. He also is known by various spellings of his family name: Thomas Haemerkken; Thomas Hammerlein; Thomas Hemerken and Thomas Hämerken.
Thomas was born at the Lower Rhine town of Kempen, Germany, in the sovereign Prince-Archbishopric of Cologne about A.D. 1380. His surname was Hemerken, Kleverlandish for little hammer. His father John was a blacksmith and his mother, Gertrude was a school-mistress.
In 1392 Thomas followed his brother, Jan, to Deventer in the Bishopric of Utrecht, in order to attend the noted Latin school. While attending school in Deventer, Thomas encountered the Brethren of the Common Life, followers of Gerard Groote's Modern Devotion. He attended school in Deventer from 1392 to 1399.
After leaving school, Thomas went to the nearby city of Zwolle to visit his brother again, after Jan had become the prior of the Monastery of Mount St. Agnes there. This community was one of the Canons Regular of the Congregation of Windesheim, founded by disciples of Groote in order to provide a way of life more in keeping with the norms of monastic life of the period. Thomas himself entered Mount St. Agnes in 1406. He was not ordained a priest, however, until almost a decade later. He became a prolific copyist and writer. Thomas received Holy Orders in 1413 and was made sub-prior of the monastery in 1429.
The monastery was disturbed for a time because of the pope's rejection of the Bishop-elect of Utrecht, Rudolf van Diepholt; otherwise, Thomas's life was a quiet one, his time being spent between devotional exercises, composition, and copying. He copied the Bible no fewer than four times, one of the copies being preserved at Darmstadt, Germany in five volumes. In its teachings he was widely read and his works abound in Biblical quotations, especially from the New Testament.
Thomas died in 1471 near Zwolle in the Prince-Bishopric of Utrecht, seventy-five miles north of his birthplace.