DEVIL IN DETAILS
This American slang term means that it is often the small details of something which make it difficult or most challenging. These details can prolong a task, or foil an otherwise straightforward deals. Like many proverbs which involve the devil, it is meant to sound a note of caution.
This reminder is intended to encourage the scientists to check their work, and to be thorough and careful. Warning: Does a nuclear deal with Iran signify a prelude to war?
Who Got What They Wanted in the Iran Nuclear Deal http://nyti.ms/1L7kOir