The editor of a local free magazine, in which Leonore has been publishing articles about exercise and nutrition, asked me to do a monthly, brief definition of a word of phrase, under the heading David's Definitions.
The first one will be in the April issue. Here it is:
Or nit-picking, or nit picking, or picking nits.
Nits are lice eggs. In the old days, people used to get rid of lice infestations on their kids' heads by shaving off all the hair and then picking off the nits, so that there wouldn't be another generation of lice. (The parents had to pick the nits off because lice use their saliva to glue their eggs to your scalp. Lice don't find that disgusting.) So nitpicking is looking for tiny details.