There is an order in the mode of subsistence of the Three Persons, which cannot be reversed, and properties that cannot be interchanged, an order of relationship. This is not to be construed as subordination, however. These distinctions between the Persons are not distinctions of essence, but of person. They are “the same in substance, equal in power and glory.” The essence of God involves infinite, eternal, and unchangeable being and perfection. The fact that we recognize each of these persons as deity implies that there can be no subordination of essence.
The economic relations reveal appropriate distinctions, which rest upon these eternal personal distinctions. It is the Father who is usually thought of as the source of creation. The Son is the one who has come to do the bidding of the Father in the Covenant of Grace, and the Holy Spirit is sent by both the Father and the Son to apply the work of redemption accomplished by the Son.
Systematic Theology, Vol I, p. 153.