Thomas Hammerken (or Hammerlein -- both mean "little hammer") was born at Kempen (hence the "A Kempis") in the duchy of Cleves in Germany around 1380. He was educated by a religious order called the Brethren of the Common Life, and in due course joined the order, was ordained a priest, became sub-prior of his house (in the low Countries), and died 25 July 1471 (his feast is observed a day early to avoid conflict with that of James bar-Zebedee the Apostle).
Thomas is known almost entirely for composing or compiling a manual of spiritual advice known as The Imitation of Christ, in which he urges the reader to seek to follow the example of Jesus Christ and to be conformed in all things to His will. An extract follows:
When God bestows Spiritual comfort, receive it with a grateful heart; but remember that it comes of God's free gift, and not of your own merit. Do not be proud, nor over joyful, nor foolishly presumptuous; rather, be the more humble for this gift, more cautious, and more prudent in all your doings, for this hour will pass, and temptation will follow it. When comfort is withdrawn, do not immediately despair, but humbly and patiently await the will of Heaven; for God is able to restore you to a consolation even richer than before. This is nothing new or strange to those who know the ways of God, for the great Saints and Prophets of old often experienced these changes. ...Indeed, the temptation that precedes is often a sign of comfort to follow. For heavenly comfort is promised to those who have been tried and tempted."To him who overcomes," says God, "I will give to eat of the Tree of Life."
Prayer (traditional language)
Holy Father, who hast nourished and strengthened thy Church by the writings of thy servant Thomas a Kempis: Grant that we may learn from him to know what we ought to know, to love what we ought to love, to praise what highly pleaseth thee, and always to seek to know and follow thy will; through Jesus Christ our Lord, who liveth and reigneth with thee and the Holy Spirit, one God, for ever and ever.Prayer (contemporary language)
Holy Father, who have nourished and strengthened your Church by the writings of your servant Thomas a Kempis: Grant that we may learn from him to know what we ought to know, to love what we ought to love, to praise what highly pleases you, and always to seek to know and follow your will; through Jesus Christ our Lord, who lives and reigns with you and the Holy Spirit, one God, for ever and ever.Psalm 34:1-8 or 33:1-5,20-21