carry fire in one hand and water in the other：
To be duplicitous, to engage in double-dealing; to be two-faced, to speak with forked tongue. The expression comes from Plautus; it continues “to bear a stone in one hand, a piece of bread in the other.” Thus, the expression indicates that a person is prepared to act in totally contradictory ways to achieve his purposes.
To say one thing and mean another; to flatter, to deceive; to lull suspicion in order the better to work mischief.
[disingenuous]---not open or sincere; slightly dishonest and untruthful
The small man says in his heart: "If I just say to someone that they are wise but think to myself that he is really a fool, then I'd consider that a deliberate act of saying one thing and thinking another."