Danielou and Tertullian's Christology

Jean Danielou tellingly writes these words about Tertullian's doctrine of God and Christ:

"The Son and the Spirit are distinguished, therefore, from the Father in that they have their own subsistent being, which is not, however, based on their eternal specific individuality, but rather on their function in relation to God's creation. Tertullian does not manage to get beyond the combination of a modalism with regard to the distinctness of the individual persons and a subordinationism with regard to their existential plurality" (Danielou, The Origins of Latin Christianity, 364).