Prologue 11 V. P ractical D irections for U sing T his C atechism 18 This catechism is conceived as an organic presentation of the Catholic faith in its entirety. It should be seen therefore as a unified whole. Numerous cross-references in the margin of the text (itali- cized numbers referring to other paragraphs that deal with the same theme), as well as the analytical index at the end of the volume, allow the reader to view each theme in its relationship with the entirety of the faith. 19 The texts of Sacred Scripture are often not quoted word for word but are merely indicated by a reference ( cf .). For a deeper understanding of such passages, the reader should refer to the Scriptural texts themselves. Such Biblical references are a valuable working-tool in catechesis. 20 The use of small print in certain passages indicates observations of an historical or apologetic nature, or supplementary doctrinal explana- tions. 21 The quotations , also in small print, from patristic, liturgical, magisterial or hagiographical sources, are intended to enrich the doctrinal presentations. These texts have often been chosen with a view to direct catechetical use. 22 At the end of each thematic unit, a series of brief texts sum up the essentials of that unit’s teaching in con- densed formulae. These IN BRIEF summaries may suggest to local catechists brief summary formulae that could be memorized. VI. N ecessary A daptations 23 The Catechism emphasizes the exposition of doctrine. It seeks to help deepen understanding of faith. In this way it is oriented toward the maturing of that faith, its putting down roots in personal life and its shining forth in personal conduct. 17 24 By design, this Catechism does not set out to provide the adaptation of doctrinal presentations and catechetical methods required by the differences of culture, age, spiritual maturity, and social and ecclesial condition among all those to whom it is ad- dressed. Such indispensable adaptations are the responsibility of particular catechisms and, even more, of those who instruct the faithful: 17 Cf. CT 20-22, 25.