The eternal generation of the Son is defined as "an eternal personal act of the Father, wherein, by necessity of nature, not by choice of will, He generates the person (not the essence) of the Son, by communicating to Him the whole indivisible substance of the Godhead, without division, alienation, or change, so that the Son is the express image of His Father's person, and eternally continues, not from the Father, but in the Father, and the Father in the Son."