Among the many expressions, idioms, aphorisms, etc. that come from Shakespeare, I think I may have found one that wasn't even intentional. I've never been convinced by the origins given for the phrase "brand new" in dictionaries - any that I've seen anyway. Some quote Shakespeare, correctly, as having used the expression "fire-new" several times. From there, the theory goes that people began to use the image of a brand as a substitute for fire - but why? And where is the first recorded use? Well, in sonnet 153 the two words appear together, but "brand" is used as a noun, not an adverb. It seems strange, but it may be that just the fact that they appeared together in a Shakespeare poem began their linked usage. Here's the poem:

Cupid laid by his brand, and fell asleep:

A maid of Dian's this advantage found,

And his love-kindling fire did quickly steep

In a cold valley-fountain of that ground;

Which borrow'd from this holy fire of Love

A dateless lively heat, still to endure,

And grew a seething bath, which yet men prove

Against strange maladies a sovereign cure.

But at my mistress' eye Love's brand new-fired,

The boy for trial needs would touch my breast;

I, sick withal, the help of bath desired,

And thither hied, a sad distemper'd guest,

But found no cure: the bath for my help lies

Where Cupid got new fire--my mistress' eyes.

The line in question refers to Cupid's brand, which had been put out by a maid of Dian's thus giving birth to healing hot springs ("a seething bath"), being reignited ("new-fired") by the eyes of the poet's mistress. The poet visits the bath hoping for a cure, but can only find it "Where Cupid got new fire - my mistress' eyes". Quite a poem, isn't it? I don't know that my theory is right, but I kind of hope so.