These pages, now collected in one small volume, have been written for the purpose of helping the faithful, ordinary souls, to attain one most important object: active participation in the holy Sacrifice of the Mass; so that, consciously and deliberately, they may offer the sacred Victim, offer themselves and be nourished by receiving the holy Eucharist. In a word: that they may live the blessed Eucharist, the sacrifice and the sacrament, in its entirety, and that by living it they may sanctify themselves more and more, for that is the will of God: Haec est voluntas Dei, sanctificatio vestra (I Thess. IV, 3). In writing these pages, I have been inspired by a heartfelt desire to do something for the good of souls: to make the holy Mass better known and consequently more deeply loved and lived, for it is the centre of all our worship, the soul of our religion, the complete programme of our sanctity and a wonderful summary of dogma and morals. If I succeed in this I shall have co-operated in spreading the kingdom of God among men and disposed recognition of God's rights over their lives. - From the Preface