μετὰ τὸν υἱόν.  So the Benedictine text with four mss. in the Paris Library, and the note.  “μετὰ τοῦ υἱοῦ” is a reading which is inadmissible, repeating as it does the sense of the following clause καὶ σὺν αὐτῷ.  The sense in which the Son is both “after the Son” and “with the Son” is explained further on by St. Basil, where he says that the three Persons are known in consecution of order but in conjunction of nature.