Basil and Gregory were close friends; but in his eagerness to see his friend installed as a bishop near himself, Basil more or less forced Gregory to take up the insignificant see of Sasima near Caesarea, a fate to which he consigned his brother (also called Gregory, who was installed as bishop in insignificant Nyssa). Gregory found the post distasteful and resigned from it, and the two friends were not quite so close after that. Nazianzen, in particular, seemed to feel that Basil had used him to shore up his position in the area -- and, unfortunately, this may not be wholly untrue. But Basil has many sterling qualities. The following is from his theological masterpiece, On the Holy Spirit:
For we do not count by way of addition, gradually making increase from unity to multitude, and saying one, two, and three,—nor yet first, second, and third. For “I,” God, “am the first, and I am the last.” And hitherto we have never, even at the present time, heard of a second God. Worshipping as we do God of God, we both confess the distinction of the Persons, and at the same time abide by the Monarchy. We do not fritter away the theology in a divided plurality, because one Form, so to say, united in the invariableness of the Godhead, is beheld in God the Father, and in God the Only begotten. For the Son is in the Father and the Father in the Son; since such as is the latter, such is the former, and such as is the former, such is the latter; and herein is the Unity. So that according to the distinction of Persons, both are one and one, and according to the community of Nature, one. How, then, if one and one, are there not two Gods? Because we speak of a king, and of the king’s image, and not of two kings. The majesty is not cloven in two, nor the glory divided. The sovereignty and authority over us is one, and so the doxology ascribed by us is not plural but one; because the honour paid to the image passes on to the prototype. Now what in the one case the image is by reason of imitation, that in the other case the Son is by nature; and as in works of art the likeness is dependent on the form, so in the case of the divine and uncompounded nature the union consists in the communion of the Godhead. One, moreover, is the Holy Spirit, and we speak of Him singly, conjoined as He is to the one Father through the one Son, and through Himself completing the adorable and blessed Trinity. Of Him the intimate relationship to the Father and the Son is sufficiently declared by the fact of His not being ranked in the plurality of the creation, but being spoken of singly; for he is not one of many, but One. For as there is one Father and one Son, so is there one Holy Ghost. He is consequently as far removed from created Nature as reason requires the singular to be removed from compound and plural bodies; and He is in such wise united to the Father and to the Son as unit has affinity with unit.