The Mysticism I speak on in the following pages is Catholic Mysticism. Not any sort of Catholic or would-be-Catholic Mysticism: but Catholic Traditional Mysticism. Two questions will arise at once in the minds of some readers: Is there a Catholic Traditional Mysticism? and if so, in what does it differ from any other mysticism? For, with many people, the conviction prevails, and is strongly rooted, that Mysticism is a relatively modern discovery, and was quite unknown to the medieval Doctors, let alone the Fathers of the Church and the Christians of the first centuries.