To all the arguments of the Latins that when they teach that the Holy Spirit proceeds from both the Father and the Son, they do not teach two causes of the Holy Spirit but one, Saint Mark answered, and is it possible for one cause to come from two persons? Is this not a commingling of the hypostases? This is the dogma of Sabellios. 73 Saint Mark understood what the basis for the Filioque was and according to him it taught a confusion of the hypostatic modes of existence. in continuation he stated:
if then, the unique source of the super-essential Godhead is the Father, and in this He is distinguished from the Son and the Spirit, what was the objective of this radical distinction? The Son cannot partake of the source of the Father, nor can the Holy Spirit do so, for thus, there is a confusion concerning the divine persons, and the distinctions are abolished. For as he says, neither is it lawful that those things which are united be abolished, nor can those things which are distinguished (from one another) be confused. And for this reason, (the matter) of the source of the Godhead can in no way be attributed to the Son. 74