rarndt01:
So one of the councils, I believe the council of Trent made a change and decreed that the blood and body would now be accessible in one species. And it pretty much has remained that way ever since.
The Catechism of the Council of Trent has this to say:
Why the Celebrant Alone Receives Under Both Species
It is clear that the Church was influenced by numerous and most cogent reasons, not only to approve, but also to confirm by authority of its decree, the general practice of communicating under one species.
(Spilling is given as the first reason)
(Next is that the Eucharist species of wine might turn acidy after a long time, as it is often held in readiness for the sick)
(Next is the fact that many cannot at all bear the taste or smell of wine, so that which is meant for spiritual health should not be required when it results in physical hurt)
(Next is that wine is extremely scarce or expensive in many countries, but bread is very common)
Finally, a most important reason was the necessity of opposing the heresy of those who denied that Christ, whole and entire, is contained under either species, and asserted that the body is contained under the species of bread without the blood, and the blood under the species of wine without the body. In order, therefore, to place more clearly before the eyes of all the truth of the Catholic faith, Communion under one kind, that is, under the species of bread, was most widely introduced.
That’s p. 252 in my copy of the CCT.
See also, Summa Theologica 3A 80, 12
newadvent.org/summa/408012.htm
Whether it is lawful to receive the Body without the Blood?
and
newadvent.org/summa/407602.htm
Is the entire Christ under each species of the Eucharist?
Obviously, he shouldn’t be taken to mean Consubstantiation when the word “under” is used!
Also note, Aquinas was about 300 years prior to the Council of Trent.