The Bondage of the Will, by Martin Luther, is one of my favorites. The particular version I have read, and enjoyed, is translated(from the original Latin) by J. I. Packer and O. R. Johnston. Luther wrote the book in response to a work by Desiderius Erasmus , Diatribe seu collatio de libero arbitrio(Discussion, or Collation, concerning Free-Will), who defended the idea that man has a free will, is not in bondage to sin and that his choices, good or bad, are not determined by God. Luther's reply De servo arbitrio(On the Bondage of the Will), thoroughly critiques Erasmus's 'Diatribe', (as Luther terms it) and shows the absurdity of his arguments. Luther defends God's freedom, and asserts than man is not free but a slave to his own desires.
All in all, Luther does an excellent job at asserting the bondage of man to sin, and defending the freedom of God, God's right to do with man whatever He pleases. "God is He for Whose will no cause or ground may be laid down as its rule and standard; for nothing is on a level with it or above it, but it is itself the rule for all things. If any rule or standard., or cause or ground, existed for it, it could no longer be the will of God. What God wills is not right because He ought, or was bound, so to will; on the contrary, what takes place must be right, because He so wills it. Causes and grounds are laid down for the will of the creature, but not for the will of the Creator - unless you set another Creator over Him!"( Martin Luther, The Bondage of the Will[Grand Rapids Michigan: Fleming H. Revell a division of Baker Book House Company, Sixteenth Printing 2004], 209.) I highly recommend this work.
This book may be read in e-book form
At Google books
This book may be purchased at (note that there are other translations/versions, but I like the one translated by Packer the best)