I hope this helps
From the Catechism (get yourself a copy btw if you can)
1376 The Council of Trent summarizes the Catholic faith by declaring: "Because Christ our Redeemer said that it was truly his body that he was offering under the species of bread, it has always been the conviction of the Church of God, and this holy Council now declares again, that by the consecration of the bread and wine there takes place a change of the whole substance of the bread into the substance of the body of Christ our Lord and of the whole substance of the wine into the substance of his blood. This change the holy Catholic Church has fittingly and properly called
transubstantiation."206
1381 "That in this sacrament are the true Body of Christ and his true Blood is something that ‘cannot be apprehended by the senses,’ says St. Thomas, ‘but only by faith, which relies on divine authority.’ For this reason, in a commentary on Luke 22:19 (‘This is my body which is given for you.’), St. Cyril says: ‘Do not doubt whether this is true, but rather receive the words of the Savior in faith, for since he is the truth, he cannot lie.’"212
Godhead here in hiding, whom I do adore
Masked by these bare shadows, shape and nothing more,
See, Lord, at thy service low lies here a heart
Lost, all lost in wonder at the God thou art.
Seeing, touching, tasting are in thee deceived;
How says trusty hearing? that shall be believed;
What God’s Son has told me, take for truth I do;
Truth himself speaks truly or there’s nothing true.213
Read the rest
here if you want