“The holy Eucharist completes Christian initiation” (Catechism of the Catholic Church, 1322).
“The Eucharist is the ‘source and summit of the Christian life’. The other sacraments, and indeed all ecclesiastical ministries and works of the apostolate, are bound up with the Eucharist and are oriented toward.” (Catechism of the Catholic Church, 1324)
If from the beginning Christians have celebrated the Eucharist and in a form whose substance has not changed despite the great diversity of times and liturgies, it is because we know ourselves to be bound by the command the Lord gave on the eve of his Passion: “Do this in remembrance of me.”
We carry out this command of the Lord by celebrating the memorial of his sacrifice. In so doing, we offer to the Father what he has himself given us: the gifts of his creation, bread and wine which, by the power of the Holy Spirit and by the words of Christ, have become the body and blood of Christ. Christ is thus really and mysteriously made present.
We must therefore consider the Eucharist as:
thanksgiving and praise to the Father; the sacrificial memorial of Christ and his Body;
the presence of Christ by the power of his word and of his Spirit.
(Catechism of the Catholic Church, 1356, 1357, 1358).
The decision concerning an individual child’s readiness to receive First Communion rests in the first place with the child’s parents in consultation with the child’s parish priest and teacher(s). However, it is the duty of the parish priest to see to it that children who have not yet reached the use of reason, or whom he has judged to be insufficiently prepared, do not come to Holy Communion (canon 914).
Adequate preparation (in the Archdiocese of Toronto) is understood to be the successful completion of the initial preparation for this sacrament (either in a Catholic school or in a parish) and of the immediate preparation provided by the parish for all First Communion candidates (e.g. enrolment of all candidates for First Eucharist and, where these exist, additional classes). (Norms for Sacramental Preparation, Archdiocese of Toronto, 76)