I went to the Colorado Mountain Clubs 10 Essentials and they referred to the list from 1974 itemized in the book, Mountaineering, The Freedom of the Hills
I have no idea how I could carry everything that was recommended.

1. Navigation: map, altimeter, compass, [GPS device], [PLB, satellite communicator, or satellite phone], [extra batteries or battery pack]
2. Headlamp: plus extra batteries
3. Sun protection: sunglasses, sun-protective clothes, and sunscreen
4. First aid: including foot care and insect repellent (if required)
5. Knife: plus repair kit
6. Fire: matches, lighter and tinder, or stove as appropriate
7. Shelter: carried at all times (can be a lightweight emergency bivy)
8. Extra food: beyond minimum expectation
9. Extra water: beyond minimum expectation, or the means to purify
10. Extra clothes: sufficient to survive an emergency overnight