in a nutshell Concisely, tersely, pithily; briefly, simply, in few words; containing much of substance in a small space, as nutmeat within a nutshell. Nutshell as representative of conciseness has been in use since the 17th century; the phrase in a nutshell since shortly thereafter.

nature of the beast The essence of a person or thing; human nature; the qualities and characteristics common to human beings and other animals. This expression combines nature ‘essential qualities or properties’ and beast ‘any animal,’ implying that there is a certain crudeness common to all animals, both human and nonhuman. It is often used in the context of explaining or excusing the behavior of someone who acts or has acted in an inappropriate or boorish manner. Such usage is illustrated in a 1683 letter by Jules Verney:

In recent years, the usage of nature of the beast has been extended to describe the negative qualities often inherent in inanimate objects, bureaucratic systems, and other matters.

part and parcel An integral or essential component; a vital part of a larger entity. In this expression, common since the 14th century, part and parcel are synonymous, their juxtaposition serving to emphasize the importance of a given constituent to the whole.

sixty-four-dollar question The crux of the matter; the basic or critically important question; the remaining unknown whose answer would provide the ultimate solution of a problem. This expression refers to the prize awarded for correctly answering the last and most difficult in a series of questions asked of a contestant on “Take It or Leave It,” a popular radio quiz show in the 1940s. With the advent of television, the stakes were raised considerably in “The $64,000 Question” (1955-58), giving rise to the updated variation, sixty-four-thousand-dollar question.