The precise subject of this book is not immediately evident from the title. In contemporary usage, ‘pre-existence’ signifies the idea that the individual soul existed before its life on earth. The idea is expressed in the various doctrines of pre-existence and metempsychosis, from Plato and the philosophies of the East, to Gnosticism and occultism, both ancient and modern. Our concern in this work is not limited to the pre-existence of the individual soul; it encompasses any person or thing thought of as existing before its own manifestation or before the creation of the world.

At the outset we are faced with a peculiar difficulty. It is not possible to define the term ‘pre-existence’ a priori. All that can be said a priori is that ‘pre-existence’ means ‘existence before…’. The meaning of the term must be established a posteriori for every context in which it is used. Where the meaning of a term under consideration is not self-evident, one must proceed by proposing a hypothetical or working definition and refining it as the discussion develops. We shall follow this method.

Our difficulty arises from this need for a hypothetical or working definition. Such a definition should be based only on the texts; but, since the term itself never occurs in the texts, its distinctive content is not apparent from a preliminary survey. Our only recourse is to the work of scholars who have used the term before us.