'Till he did look on me.

The Duke has justly observed that Isabel is importuned against all
sense to solicit for Angelo, yet here against all sense she solicits
for him. Her argument is extraordinary.

A due sincerity govern'd his deeds,
'Till he did look on me; since it is so,
Let him not die. That Angelo had committed

all the crimes charged against him, as far as he could commit
them, is evident. The only INTENT which his act did not overtake,
was the defilement of Isabel. Of this Angelo was only intentionally
guilty. Angelo's crimes were such, as must sufficiently justify
punishment, whether its end be to secure the innocent from wrong,
or to deter guilt by example; and I believe every reader feels some
indignation when he finds him spared. From what extenuation of his
crime can Isabel, who yet supposes her brother dead, form any plea
in his favour. Since he was good 'till he looked in me, let him
not die. I am afraid our Varlet Poet intended to inculcate, that
women think ill of nothing that raises the credit of their beauty,
and are ready, however virtuous, to pardon any act which they think
incited by their own charms.

ACT V. SCENE viii. (v. i. 479 foll.)

It is somewhat strange, that Isabel is not made to express either
gratitude, wonder or joy at the sight of her brother.