Calvin: God is not bound to means

From Sovereign Grace and the Scope of Election: A Comparative Examination of Attainment Theology and Grace Theology, with Particular Attention to the Question of Whether God's Elect Are Found Among All Nations and Religions

Calvin held the preached word in the highest honor as the ordinary instrument of calling, and no honest account should soften that. But in defending the salvation of covenant infants he stated a principle larger than the case that occasioned it: God's power is not tied to outward means, and the Spirit works in elect infants a hidden seed of future repentance and faith by His secret operation (Institutes 4.16.17-20; compare 3.21-24 on election). Calvin's own example was John the Baptist, sanctified from the womb, and his own inference was that God may work savingly where the ordinary ministry of the word cannot reach. The question this document presses is simply whether that principle, once granted, can be arbitrarily confined to one age bracket.