Fifty-four years after the enthusiastic efforts at the implementations of the principle of active participation in the liturgy, certain disturbing signs abound with regard to the liturgy and how it is celebrated which do not conform with the positive effects that had been expected from the reception and implementation of this principle: More often than not the emphasis on what constitutes participation has centred more on the quantity and extent of what is done rather than the quality and content of what is done, which for me, is a false inversion. This is not in any way to relegate the role of doing something in the liturgy to the background-after all the soul always needs a body; but again, one must be able to go beyond just doing something to grasping the content of what is done or has been done. Is it possible that we have been looking at this principle from only one perspective-the external-without grasping the depths of it? Could we look at the other side: the internal and spiritual? This is what this book tries to achieve in a systematic and scholarly manner: to participate is to relate in a conscious, deliberate and active manner with Christ and all that He has revealed to us. Rev Fr Victor Usman Jamahh is a priest of the Catholic Diocese of Minna, Nigeria who holds an STD from the University of Innsbruck, Austria (2013) with specialization in Liturgy. He is presently a formator at the Good Shepherd Major Seminary in Kaduna where he is also the Dean of Studies and teaches Introduction to Liturgy, Theology of the Liturgy, Practical Liturgy, Homiletics and Medieval Church History.