The following I have just cut and past from Jim West’s blog (http://zwingliusredivivus.wordpress.com/):
Again, I know for certain that God teaches me, because I have experienced the fact of it; and to prevent misunderstanding this is what I mean when I say that I know for certain that God teaches me. When I was younger, I gave myself overmuch to human teaching, like others of my day, and when about seven or eight years ago I undertook to devote myself entirely to the Scriptures I was always prevented by philosophy and theology. But eventually I came to the point where led by Scripture and the Word of God I saw the need to set aside all these things and to learn the doctrine of God direct from his own Word.
Then I began to ask God for light and the Scriptures became far clearer to me – even though I read nothing else – than if I had studied many commentators and expositors. Note that that is always a sure sign of God’s leading; for I could never have reached that point by my own feeble understanding. You may see then that my interpretation does not derive from the over-estimation of myself, but the subjection. — Huldrych Zwingli