Tertullian

“ John’s Gospel.
What follows Philip’s question, and the Lord’s whole treatment of it, to the end of John’s Gospel, continues to furnish us with statements of the same kind, distinguishing the Father and the Son, with the properties of each. Then there is the Paraclete or Comforter, also, which He promises to pray for to the Father, and to send from heaven after He had ascended to the Father. He is called “another Comforter,” indeed; [1] but in what way He is another we have already shown, [2] “He shall receive of mine,” says Christ, [3] just as Christ Himself received of the Father’s. ”

“ Now that all the restraint of His humiliation is taken away, He might, if possible, have shown Himself as the Father to so faithful a woman (as Mary Magdalene) when she approached to touch Him, out of love, not from curiosity, nor with Thomas’ incredulity. ”

“ Thus the connection of the Father in the Son, and of the Son in the Paraclete, produces three coherent Persons, who are yet distinct One from Another. These Three are one [4] essence, not one Person, [5] as it is said, “I and my Father are One,” [6] in respect of unity of substance not singularity of number. ”