Heidelberg disputation, also of 1518, Luther
says of man's powers in spiritual matters: "13. Free will after sin [the
Fall] is a mere titular affair [an empty title only], and sins mortally
when it does what it is able to do. _Liberum arbitrium post peccatum res
est de solo titulo et dum facit, quod in se est, peccat mortaliter._"
"16. A man desirous of obtaining grace by doing what he is able to do
adds sin to sin, becoming doubly guilty. _Homo putans, se ad gratiam
velle pervenire faciendo, quod est in se, peccatum addit peccato, ut
duplo reus fiat._" "18. It is certain that a man must utterly despair of
himself in order to become apt to acquire the grace of Christ. _Certum
est, hominem de se penitus oportere desperare, ut aptus fiat ad
consequendam gratiam Christi._" (W. 1, 354.) By way of explanation
Luther added to thesis 13: "The first part [of this thesis, that free
will is a mere empty title] is apparent, because the will is a captive
and a servant to sin, not that it is nothing, but that it is free only
to [do] evil--_non quod sit nihil, sed quod non sit liberum nisi ad
malum._ John 8, 34. 36: 'Whosoever committeth sin is the servant of sin.
If the Son shall make you free, ye shall be free indeed.' Hence, St.
Augustine says in his book _De Spiritu et Litera:_ Free will without
grace can only sin--_non nisi ad peccandum valet._ And in his second
book against Julianus: You call that a free will which in truth is
captive, etc." To thesis 16 Luther added: "When man does what he is able
to do (_dum facit, quod est in se_), he sins, seeking altogether his
own. And if he is minded to become worthy of, and apt for, grace by a
sin, he adds proud presumption."

In his sermon of 1519 on Genesis 4, Luther remarked: "This passage ['The
Lord had respect unto Abel'] subverts the entire liberty of our human
will. _Hic locus semel invertit universam libertatem voluntatis
nostrae._" (Weimar 9, 337.) In a sermon of September 8, 1520, we read:
"By nature we are born accursed;... through Christ we are born again
children of life. Thus we are born not by free will, not by works, not
by our efforts. As a child in the womb is not born by its own works, but
suffers itself to be carried and to be given birth, so we are justified
by suffering, not by doing." (474.) "Where, then," Luther exclaimed
about the same time in his _Operationes in Psalmos,_ "will free will
remain? where the doing what one can? _Ubi ergo manebit liberum
arbitrium