VadeMecum

Vade Mecum
I want the scissors to be sharp
and the table perfectly level
when you cut me out of my life
and paste me in that book you always carry.

-- Billy Collins

Etymology

From the Latin vade mecum, which literally means "go with me."

Noun

vade mecum (plural vade mecums)
1. A referential book such as a handbook or manual.
2. A useful object, constantly carried on one’s person.