Which theme of the play is supported by these lines?

Present him eminence, both with eye and tongue:
Unsafe the while, that we
Must lave our honors in these flattering streams;
And make our faces vizards to our hearts,
Disguising what they are.

Darkness is dangerous.
Ambition unchecked can lead to corruption.
Things are not always what they seem.
Those without convictions are easily manipulated.

ANSWER: C