His fatal blunder was that he
did so in terms which were universally regarded as savoring of
Manicheism. As was fully explained in the chapter of the Synergistic
Controversy Strigel taught that free will, which belongs to the
substance and essence of man, and hence cannot be lost without the
annihilation of man himself, always includes the capacity to choose in
both directions, that also with respect to divine grace and the
operations of the Holy Spirit man is and always remains a _liberum
agens_ in the sense that he is able to decide _in utramque partem;_ that
this ability, constituting the very essence of free will, may be
weakened and impeded in its activity, but never lost entirely. If it
were lost, Strigel argued, the very substance of man and free will as
such would have to be regarded as annihilated. But now man, also after
the Fall, is still a real man, possessed of intellect and will. Hence
original sin cannot have despoiled him of this liberty of choosing _pro_
or _con_ also in matters spiritual. The loss of original righteousness
does not, according to Strigel, involve the total spiritual disability
of the will and its sole tendency and activity toward what is
spiritually evil. Moreover, despite original corruption, it is and
remains an indestructible property of man to be able, at least in a
measure, to assent to and to admit, the operations of the Holy Spirit,
and therefore and in this sense to be converted "_aliquo modo volens._"
(Planck 4, 667. 675. 681.)

It was in opposition to this Semi-Pelagian teaching that Flacius
declared original sin to be not a mere accident, but the substance of
man. Entering upon the train of thought and the phraseology suggested by
his opponent, he called substance what in reality was an accident,
though not an accident such as Strigel contended. From his own
standpoint it was therefore a shrewd move to hide his own synergism and
to entrap his opponent, when Strigel plied Flacius with the question
whether he denied that original sin was an accident. For in the context
and the sense in which it was proposed the question involved a vicious
dilemma. Answering with yes or no, Flacius was compelled either to
affirm Strigel's synergism or to expose himself to the charge of
Manicheism. Instead of replying as he did, Flacius should have cleared
the sophistical atmosphere by explaining: "If I say, 'Original sin is an
accident,' you [Strigel] will infer what I reject, _viz._, that the