No man ever circumcised his own heart. No man can say he began to do it by the power of his own will, and then God only helped him by his grace. As the act of outward circumcision on the body of a child was the act of another, and not of the child who was only passive therein [but the effect was on the body of the child only], so it is in the spiritual circumcision—it is the act of God, in which our hearts are the subject. It is the blindness, obstinacy, and stubbornness in sin that is in us by nature, with the prejudices which possess our minds and affections, which hinder us from conversion to God. But by the circumcision, they are taken away. —John Owen