Commonality of the Divine Essence
The generation of the Son and procession of the Spirit, he says, is to be understood as "communication of the divine essence": "The term communication must be taken etymologically. By generation the Father makes the eternal essence common (koinonia) to himself and the Son."
Kevin Giles, The Eternal Generation of the Son: Maintaining Orthodoxy in Trinitarian Theology (Downers Grove, IL: InterVarsity Press, 2012), 7