Faith melts our will into God's. It runs at God's call. It not only believes God's promise, but obeys his command. The true obedience of faith is a cheerful obedience. God's commands do not seem grievous.
Faith is an assimilating grace.
Never did any look upon Christ with a believing eye, but he was made like Christ. As the chameleon is changed into the colour of that which it looks upon, so faith, looking on Christ, changes the Christian into the similitude of Christ. Growth of faith is judged by strength. We can do that now, which we could not do before. But I fear I have no faith.