get down to brass tacks

The story

The origin is uncertain. It is probably a variant of the earlier term down to the brass (see, for example, the 1854 quotation), and the following etymologies have been suggested: * The term refers to the brass tacks used in upholstery which have to be removed when a piece of furniture is reupholstered, or brass tacks stuck into the counter of a draper’s shop or hardware store to measure items precisely in yards. * Another possibility is that the brass tacks are nails used to seal coffin lids, or tacks used to decorate or indicate a deceased person’s initials on such lids, and thus the term refers to dealing with matters as serious as death.