John of Damascus definitely “starts with” the unity of the divine nature. In his Exposition of the Orthodox Faith, under the chapter heading of “Concerning the Holy Trinity,” John writes:
We believe, then, in One God, one beginning, having no beginning, uncreate, unbegotten, imperishable and immortal, everlasting, infinite, uncircumscribed, boundless, of infinite power, simple, uncompound, incorporeal, without flux, passionless, unchangeable, unalterable, unseen, the fountain of goodness and justice, the light of the mind, inaccessible; a power known by no measure, measurable only by His own will alone (for all things that He wills He can), creator of all created things, seen or unseen, of all the maintainer and preserver, for all the provider, master and lord and king over all, with an endless and immortal kingdom: having no contrary, filling all, by nothing encompassed, but rather Himself the encompasser and maintainer and original possessor of the universe, occupying all essences intact and extending beyond all things, and being separate from all essence as being super-essential and above all things and absolute God, absolute goodness, and absolute fulness: determining all sovereignties and ranks, being placed above all sovereignty and rank, above essence and life and word and thought: being Himself very light and goodness and life and essence, inasmuch as He does not derive His being from another, that is to say, of those things that exist: but being Himself the fountain of being to all that is, of life to the living, of reason to those that have reason; to all the cause of all good: perceiving all things even before they have become: one essence, one divinity, one power, one will, one energy, one beginning, one authority, one dominion, one sovereignty, made known in three perfect subsistences and adored with one adoration, believed in and ministered to by all rational creation, united without confusion and divided without separation (which indeed transcends thought). (We believe) in Father and Son and Holy Spirit whereinto also we have been baptized. For so our Lord commanded the Apostles to baptize, saying, Baptizing them in the name of the Father, Son, and Holy Spirit.
~ Exposition of the Orthodox Faith 1.8
Notice that he says there is one energy. This is because the energy is an attribute of the one essence.