What do great Christians have in common? What motivates and empowers some believers to lead extraordinary lives of service, sacrifice, and devotion? James Gilchrist Lawson (1874-1946) studied many such spiritual giants, looking for a common thread in their experience. He found that all of them had been nominal Christians until the Holy Spirit transformed their lives. They called this experience "full consecration," "entire sanctification," "the baptism of the Holy Spirit," and so on. This book describes what Lawson learned as he studied the deeper spiritual experiences of these Christian leaders.