There is no doctrine in Christian theology, as the author admits, which is so beset with difficulties and obscurities as the doctrine of the Holy Spirit. ""When we say Spirit, we mean life,"" he says, ""whatever else we may mean, Life is the ultimate mystery, which defies reduction to a formula; we may point toward it and describe it but in the end it must speak for itself. If the Holy Spirit means the Fiving nation of God in the world, our formulations cannot hope to catch up with reality."" Nonetheless, Dr. Hendry proceeds with insight and humility to try to determine what must be the basic of a Christian doctrine of the Holy Spirit. He does this by concentrating on five basic problems; 1) The problem that arises directly out of the New Testament witness to the Spirit; 2) The problem of the relation of the Spirit and God -- or the Trinitarian problem; 3) The relation between the Holy Spirit and the Church; 4) The relation of the Spirit and the Word, and 5) The relation of the Holy Spirit and the human spirit. Obviously at home in most of the significant writing that has been done on this subject, as witness his bibliography, the author has added deep insight of his own which all serious students of Christian doctrine will wish to read and study.