Tertullian (2nd century)
Then, having taken the bread and given it to His disciples, He made it His own body, by saying, This is my body, that is, the figure of my body. A figure, however, there could not have been, unless there were first a veritable body. An empty thing, or phantom, is incapable of a figure. (Against Marcion, book 4)
Clement of Alexandria (2nd century)
The Lord, in the Gospel according to John, brought this out by symbols, when He said: ‘Eat ye my flesh, and drink my blood;’ describing distinctly by metaphor the drinkable properties of faith and the promise, (Instructor)
Eusebius (4th century)
‘His eyes are cheerful from wine,’ seems to me to shew the gladness of the mystic wine which He gave to His disciples, when He said, ‘Take, drink; this is my blood that is shed for you for the remission of sins: this do in remembrance of me.’ And, ‘His teeth are white as milk,’ shew the brightness and purity of the sacramental food. For again, He gave Himself the symbols of His divine dispensation to His disciples, when He bade them make the likeness of His own Body. For since He no more was to take pleasure in bloody sacrifices, or those ordained by Moses in the slaughter of animals of various kinds, and was to give them bread to use as the symbol of His Body (Demonstratio Evangelica)
Theodoret (5th century)
For even after the consecration the mystic symbols are not deprived of their own nature; they remain in their former substance figure and form; they are visible and tangible as they were before. (Dialogues)