What is the doctrine of transubstantiation and why should it be rejected?

The forty-seventh question in our catechism is:
“What is the doctrine of transubstantiation and why should it be rejected?”
The answer is:
“Transubstantiation is the supposed change of the substance of bread and wine in the Lord’s Supper. Transubstantiation is to be rejected because it cannot be proved by Scripture, is contrary to the plain words of Scripture, goes against the nature of a sacrament, and has given rise to many superstitions..”
cf. 1 Corinthians 11:26; Acts 3:21; John 6:62-63; Acts 19:26 and Article 28.
