The signs of revelation in Christ -- the miracles, prophecies, the message itself -- are fundamental to the meaning of Christianity. There are two signs, however, in which all the others are contained implicitly: Christ himself, and the Church. And it is these two which the author discusses in this work -- from the point of view of the meaning of Christianity, and from the coherence conferred on them by Vatican II. Christ himself is approached both as the manifestation of God on earth and as the proof of this manifestation. The Church is discussed as an ensemble of probative characteristics, the chief of which is the sign par excellence, holiness of life. Tiffs, obviously, is a work for the theologian, dealing with concepts that are familiar to him in language that he understands. As a vitally needed updating of the classical problem in fundamental theology, it should be welcomed by both teachers and students.