There are several online resources for determining the origin of common phrases as of 2015, including Phrases.org.uk and Etmyonline.com. Both websites provide scholarly researched and professionally curated lists of sayings, idioms and common phrases. Websites devoted to history and news organizations also occasionally publish lists detailing the etymology of particular sayings.
Discovering the precise origin of a phrase can be difficult because some of the most common idioms trace their roots back to the earliest forms of the English language. Additionally, the stories behind such quips are often apocryphal at best. For these, scholars attempt to mark the earliest recorded examples of their use. Unsurprisingly, Shakespeare is a common source for many of these phrases.
Even phrases born during the modern era can have murky backgrounds. For example, the origin of the phrase "the whole nine yards" has proven to be particularly elusive. Several theories exist, but none have provided solid enough evidence to refute their competitors.
Many of the most common phrases began as jargon in a particular discipline, but they were adopted by the broader population. Nautical terms such as "batten down the hatches" and "walk the plank" are two popular examples. A large number of idioms are also drawn from one of the most historically influential books, the Bible. Expressions such as "a wolf in sheep's clothing," "ashes to ashes" and "old as the hills" source to common Bible translations.