I'm reading Robert Leatham's The Holy Trinity (P&R 2004) at the moment. This passage from one of the great Cappadocian theologians "vastly delighted" John Calvin:
Besides all this and before all, keep I pray you the good deposit, by which I live and work, and which I desire to have as the companion of my departure; with which I endure all that is so distressful, and despise all delights; the confession of the Father and the Son and the Holy Ghost. This I commit unto you to-day; with this I will baptize you and make you grow. This I give you to share, and to defend all your life, the One Godhead and Power, found in the Three in Unity, and comprising the Three separately, not unequal, in substances or natures, neither increased nor diminished by superiorities or inferiorities; in every respect equal, in every respect the same; just as the beauty and the greatness of the heavens is one; the infinite conjunction of Three Infinite Ones, Each God when considered in Himself; as the Father so the Son, as the Son so the Holy Ghost; the Three One God when contemplated together; Each God because Consubstantial; One God because of the Monarchia. No sooner do I conceive of the One than I am illumined by the Splendour of the Three; no sooner do I distinguish Them than I am carried back to the One. When I think of any One of the Three I think of Him as the Whole, and my eyes are filled, and the greater part of what I am thinking of escapes me. I cannot grasp the greatness of That One so as to attribute a greater greatness to the Rest. When I contemplate the Three together, I see but one torch, and cannot divide or measure out the Undivided Light.
From Gregory of Nazianzus' (ca. 330-391) Orations 40.41