Is this REALLY a quote from one of Shakepeare's works, or was I misinformed as a child . . . ? Thanks
Not a quote from Shakespeare. Can't say if it is really a "quote" or just a witticism that can be labeled "orig. unk."
I didn't find it anywhere by Shakespeare, but I have found it attributed to Joseph Addison (1672-1719).
I have also failed to find it in Shakespeare. On a totally different mission I stumbled upon this from As You Like It, Act V. Scene I. I used the first part -- "'So so' ... so so." -- for my purposes, but thought you might enjoy the second exchange where William's claim to wit is negated in a similar way to your quote.
Touch. ‘So so,' is good, very good, very excellent good: and yet it is not; it is but so so. Art thou wise? 20
Will. Ay, sir, I have a pretty wit.
Touch. Why, thou sayest well. I do now remember a saying, ‘The fool doth think he is wise, but the wise man knows himself to be a fool.'