You are not what you seem.
So many people have said that that I'm beginning to think that's precisely how I do seem. What is it I seem to be that you have now discovered that I'm not?

What seems is not what is. People are not what they appear to be.

"Seems," madam? Nay, it is; I know not "seems."
'Tis not alone my inky cloak, good mother,
Nor customary suits of solemn black,
Nor windy suspiration of forced breath,
No, nor the fruitful river in the eye,
Nor the dejected 'havior of the visage,
Together with all forms, moods, shapes of grief,
That can denote me truly: these indeed seem,
For they are actions that a man might play:
But I have that within which passeth show;
These but the trappings and the suits of woe.

You are but an appearance, and not absolutely the thing you appear to be.

Be as you wish to seem

To be rather than to seem.

To be rather than to seem.

Be, rather than seem

You see, there’s a fundamental connection between seeming and being. Every Fae child knows this, but you mortals never seem to see. We understand how dangerous a mask can be. We all become what we pretend to be.

"what you would seem to be" — or if you'd like it put more simply — "Never imagine yourself not to be otherwise than what it might appear to others that what you were or might have been was not otherwise than what you had been would have appeared to them to be otherwise."

"How do I know," she said at last, "that you are what you seem to be?"
"You don't," Said he. "I don't know what I seem, to you."

I am not what you see and hear.

Oh, what am I, and what are they ?
Masquers but striving to deceive
Themselves and others ; and believe
It is enough, if none shall know
The covered mass of care below.

Who am I behind this unreality? I don't know. I must be someone. And if I do not seek to live, to act or to feel, it is — believe me — so as not to disturb the already laid-down lines of my false persona.