Thomas a Kempis 
The Imitation of Christ [EPUB ebook] 

According to Wikipedia: ’The Imitation of Christ (Latin: De Imitatione Christi) by Thomas à Kempis is a Christian devotional book. It was first composed in Latin ca.1418-1427.[1][2] It is a handbook for spiritual life arising from the Devotio Moderna movement, where Kempis was a member.[3] The Imitation is perhaps the most widely read devotional work next to the Bible, [2][4] and is regarded as a devotional and religious classic