From whom does the Holy Spirit proceed, the Father alone or the Father and the Son?

Tertullian c. 155–c. 220 ADAgainst Praxeas 4.1

Let this be said of the third rank too: for I think the Spirit comes from nowhere else than from the Father through the Son.

The earliest statement on the Spirit's origin. "Through the Son" became the common Greek phrasing.

Basil of Caesarea c. 330–379 ADOn the Holy Spirit 18.47

So the way of knowing God goes from one Spirit through the one Son to the one Father. And in reverse, natural goodness, holiness by nature and royal dignity reach from the Father through the Only-begotten to the Spirit. In this way the persons are confessed and the true doctrine of the one source is not lost.

Basil speaks of how God is known and gives gifts. Whether this describes the Spirit's eternal origin is part of the later debate.

Cyril of Alexandria c. 376–444 ADOn Adoration in Spirit and Truth 1

...since the Spirit is God the Father's, and indeed the Son's too: the Spirit that pours forth substantially from both, that is, from the Father through the Son.

Cyril says "from both" and explains it as "from the Father through the Son". Latins later cited him for the filioque, Greeks for "through".

John of Damascus c. 645/675–749 ADExact Exposition of the Orthodox Faith 1.8

We say that the Holy Spirit is from the Father and call him the Spirit of the Father. We do not say the Spirit is from the Son, but we name him the Spirit of the Son ("if anyone does not have the Spirit of Christ", Romans 8:9), and we confess that he was made manifest and given to us through the Son.

The standard Greek position before the schism: from the Father, manifested through the Son.

Council of Florence (Catholic)Laetentur Caeli Decree of union with the Greeks

the holy Spirit is eternally from the Father and the Son, and has his essence and his subsistent being from the Father together with the Son, and proceeds from both eternally as from one principle and a single spiration.

A short-lived union of Greeks and Latins. It also declared that "through the Son" and "from the Son" mean the same. The Greek churches later rejected the union.

Westminster Confession (Reformed)Westminster Confession of Faith 2.3

the Holy Ghost eternally proceeding from the Father and the Son.

Protestant churches kept the Western creed with the filioque.

Encyclical of the Eastern Patriarchs (Orthodox)Encyclical of the Eastern Patriarchs 5

This novel opinion destroys the oneness from the One cause, and the diverse origin of the Persons of the Blessed Trinity

The Orthodox objection: the Father alone is the source in the Trinity.