"in madness" is a grammatically correct phrase that can be used in written English.
For example, you could use it in a sentence like this: "He descended into madness, and there was no one to help him."
When she is eventually married to someone else, Qays loses himself in madness (hence the name "Majnoon" or "Mad one") and gives up his whole life, searching for her everywhere.
As e'er I heard in madness.
Tom is not marooned in madness.
This is "reason in madness" to the very life.
Both poets and warriors specialize in madness and aggression and are necessary, yet dangerous, to society.
He wanted the creatures in "Madness" to be fascinating, not disgusting.
It's moving-in madness at Neneh Cherry's house.
Mr. Jacobi possibly overdoes the variations on childishness, particularly in the second half, when his fey, high-voiced ruminations evoke Lear's sister-in-madness, Ophelia.
-- Here are tips on how to survive, and thrive, in the madness at Comic-Con in San Diego.
Simple in theory but madness in practice, given the thousands of others with similar plans.
