many

many many a little makes a mickle numerous small contributions can have notable results. Proverbial saying, mid 13th century, the proper form of many a mickle makes a muckle. (Mickle in Scottish usage means ‘a great quantity or amount’, and pickle ‘a small quantity or amount’ is sometimes found instead of little).
many a mickle makes a muckle proverbial saying, late 18th century; an alteration of many a little makes a muckle which is actually nonsensical, since muckle is a variant of mickle and both mean ‘a large quantity or amount’.
many are called but few are chosen proverbial saying, early 17th century, often used with reference to a final process of selection from a wider pool; originally with biblical allusion to Matthew 22:14.
many hands make light work proverbial saying, mid 14th century, often used as an encouragement to join in with assistance; the opposite of too many cooks spoil the broth. The same idea is found in the words of the Greek poet Hesiod (c.700 bc), ‘more hands mean more work’, and the comment ‘many hands make a burden lighter’ is found in the Adages of the Dutch Christian humanist Erasmus (c.1469–1536).
many-headed monster the people, the populace; after Horace Epistles ‘the people are a many-headed beast.’ The term is recorded in English since the 16th century. The expression was popularized by Pope in Epistles of Horace (1737).
there's many a slip between cup and lip much can go wrong between the initiation of a process and its completion, often used as a warning. The saying is recorded in English from the mid 16th century, but a similar idea is found in classical times, as in a remark attributed to the Roman statesman and orator Cato the Elder (234–149 bc), ‘(I have often heard) that many things can come between mouth and morsel’. The comment ‘there are many things between the cup and the edge of the lip’ is attributed to the Greek epigrammatist Palladas of the 4th–5th centuries ad.

See also how many angels can dance on the head of a pin?, so many men, so many opinions, many a true word is spoken in jest, there's many a good tune played on an old fiddle, many go out for wool and come home shorn.