trying to find a turn of phrase, meaning we cannot read others intentions

[[deleted user]]

Hello, I am selfishly excited to be a new member of this group since being a Shakespeare devotee (as I assume you all probably are) must be like being a fine wine devotee or a golf player. It's difficult to just dabble in, and most people who do it, do it well and are knowledgeable!
And so I have selfish hope that from this moment until the end of time I will get most of my Shakespeare questions answered.

My question today...

I am trying to recall a line of dialogue or thought from one of His plays. The line is to the effect that"we cannot see what other people are thinking" or actually I think it was "we cannot see past any mask they might wear to hide their true intentions from us".
The issue was about who we could trust Once again Bill did it with a beautiful turn of phrase, I don't think he even used the word mask, something like "the mechanisms of the ..... can never unraveled". If someone could remember or locate this gem, I would be most grateful! Thank You!

[Christopher]

... O place, O form,
How often dost thou with thy case, thy habit,
Wrench awe from fools and tie the wiser souls
To thy false seeming! Blood, thou art blood:
Let’s write good angel on the devil’s horn:
’Tis not the devil’s crest.

[...]

ANGELO Nay, but hear me.
Your sense pursues not mine: either you are ignorant,
Or seem so craftily; and that's not good.
ISABELLA Let me be ignorant, and in nothing good,
But graciously to know I am no better.
ANGELO Thus wisdom wishes to appear most bright
When it doth tax itself; as these black masks
Proclaim an enshield beauty ten times louder
Than beauty could, display'd.

Measure for Measure Act II, sc. iv.

[Gabriel]

Hi Rich, I think it might be 'There is no art to find the mind's construction in the face' but I'm, not sure where it's from - Macbeth, perhaps

[Boar's Head]

I immediately thought of Gabriel's suggestion, too :)

It is King Duncan in Macbeth, talking about Cawdor's treachery - then, of course, he proves his point by making the same mistake again!

[[deleted user]]

Gabriel wrote: "Hi Rich, I think it might be 'There is no art to find the mind's construction in the face' but I'm, not sure where it's from - Macbeth, perhaps"

BINGO!!!! Thank you Gabriel!!! And of course from Macbeth. Thank you thank you. What an amazing way to put it... ...to find the mind's construction in the face' thanx!!!

[[deleted user]]

Boar's Head wrote: "I immediately thought of Gabriel's suggestion, too :)

It is King Duncan in Macbeth, talking about Cawdor's treachery - then, of course, he proves his point by making the same mistake again!"

Thank you Boar's Head... yes, yes, that's the one. And thanks for the ironical context!

[[deleted user]]

Christopher wrote: "... O place, O form,
How often dost thou with thy case, thy habit,
Wrench awe from fools and tie the wiser souls
To thy false seeming! Blood, thou art blood:
Let’s write good angel on the devil’s h..."

Thank you Christopher. That was not the one I was thinking of with my question, but your "...O place, O form" is another laser guided Will missile, esp. vis a vis (nonhuman) surface appearances. Have added to my mental list of favorites, Thank you Christopher!!!