Borrowing dulls the edge of husbandry

More from the maligned Polonius. He seems often characterized as shallow and perhaps glib but his "few precepts" which he recommends Laertes lodge "in thy memory" seem to have lodged in the cultural conscience down the ages to the benefit of all who have heard them, whether directly in Hamlet, through derivative paths such as Poor Richard's Almanack by Benjamin Franklin, or simply in the phrases which have slipped into common parlance.

From Act 1, Scene 3

Why put things in plain fashion when you can dress it up? Common language version: Hurry up, you're keeping everyone waiting. The Shakespearean treatment:

Aboard, aboard, for shame!
The wind sits in the shoulder of your sail,
And you are stay'd for.

Advice:

Give thy thoughts no tongue
Nor any unproportion'd thought his act.

Be thou familiar, but by no means vulgar

Those friends thou hast, and their adoption tried,
Grapple them unto thy soul with hoops of steel;
But do not dull thy palm with entertainment
Of each new-hatch'd, unfledg'd comrade.

Beware
Of entrance to a quarrel; but being in,
Bear't that th' opposed may beware of thee.

Give every man thine ear, but few thy voice

Take each man's censure, but reserve thy judgment.

Costly thy habit as thy purse can buy,
But not express'd in fancy; rich, not gaudy;
For the apparel oft proclaims the man

Neither a borrower nor a lender be;
For loan oft loses both itself and friend,
And borrowing dulls the edge of husbandry

This above all- to thine own self be true,
And it must follow, as the night the day,
Thou canst not then be false to any man.

For every concerned parent of their teen's choice of company:

Marry, well bethought!
'Tis told me he hath very oft of late
Given private time to you, and you yourself
Have of your audience been most free and bounteous.
If it be so- as so 'tis put on me,
And that in way of caution- I must tell you
You do not understand yourself so clearly
As it behooves my daughter and your honour.
What is between you? Give me up the truth.

This passage is often interpreted, probably correctly as evidence of Polonius' duplicitous character. He is asking his servant Reynaldo to go spy on Laertes and delicately probe Laertes' friends and acquaintances to find out to what extent Laertes has been drinking, whoring, gambling, etc.

Your bait of falsehood takes this carp of truth;
And thus do we of wisdom and of reach,
With windlasses and with assays of bias,
By indirections find directions out.

But when you think about it, is this perhaps not one of the first articulations of the concept of the null hypothesis which is otherwise first described in Ronald Fisher's 1935 Design of Experiments? Shakespeare the Statistician?

Love as a motive force.

This is the very ecstasy of love,
Whose violent property fordoes itself
And leads the will to desperate undertakings
As oft as any passion under heaven
That does afflict our natures.

On the tendency of the elderly and jaded to be too skeptical while the young are too gullible.

By heaven, it is as proper to our age
To cast beyond ourselves in our opinions
As it is common for the younger sort
To lack discretion.

Another line, often criticized as self-contradictory is:

My liege, and madam, to expostulate
What majesty should be, what duty is,
Why day is day, night is night, and time is time.
Were nothing but to waste night, day, and time.
Therefore, since brevity is the soul of wit,
And tediousness the limbs and outward flourishes,
I will be brief.

Put another way though: Life is full of complex issues which we don't have unlimited time to discuss them. Cutting to the chase, . . . This conundrum is at the heart of many disputations. If you define and clarify assumptions, and amass evidence with all the necessary qualifiers, you end up, in the modern parlance, with TLDR (too long, didn't read). Polonius was clearly anticipating Twitter where complex ideas a reduced, ab absurdum, to the greatest of brevity.

The Rotherham Tragedy might have been entirely prevented, had any of the British government officials, elected politicians, social services bureaucrats, or police had they read Polonius on straight speaking and calling a thing for what it is without undue nicety.

Madam, I swear I use no art at all.
That he is mad, 'tis true: 'tis true 'tis pity;
And pity 'tis 'tis true. A foolish figure!
But farewell it, for I will use no art.
Mad let us grant him then. And now remains
That we find out the cause of this effect-
Or rather say, the cause of this defect,
For this effect defective comes by cause.
Thus it remains, and the remainder thus.
Perpend.

The progressive mindset that wants to wish away unpleasant truths is captured somewhat later:

I am ill at these numbers; I have not art to
reckon my groans

Repurposing lines, you can see in this passage, a description of some people's response when their preferred belief is rebuffed by logic and evidence.

And he, repulsed, a short tale to make,
Fell into a sadness, then into a fast,
Thence to a watch, thence into a weakness,
Thence to a lightness, and, by this declension,
Into the madness wherein now he raves,

Another line which has endured:

Though this be madness, yet there is a method in't.