"A bird in the hand is worth two in the bush" （一鳥在手，勝過百鳥在林。）
It's better to have a small real advantage than the possibility of a greater one.
his proverb refers back to mediaeval falconry where a bird in the hand (the falcon) was a valuable asset and certainly worth more than two in the bush (the prey).
The first citation of the expression in print in its currently used form is found in John Ray's A Hand-book of Proverbs, 1670, which he lists it as:
A [also 'one'] bird in the hand is worth two in the bushBy how much the phrase predates Ray's publishing isn't clear, as variants of it were known for centuries before 1670. The earliest English version of the proverb is from the Bible and was translated into English in Wycliffe's version in 1382, although Latin texts have it from the 13th century:
Ecclesiastes IX - A living dog is better than a dead lion.Alternatives that explicitly mention birds in hand come later. The earliest of those is in Hugh Rhodes' The Boke of Nurture or Schoole of Good Maners, circa 1530:
"A byrd in hand - is worth ten flye at large."John Heywood, the 16th century collector of proverbs, recorded another version in his ambitiously titled A dialogue conteinyng the nomber in effect of all the prouerbes in the Englishe tongue, 1546:
"Better one byrde in hande than ten in the wood."The Bird in Hand was adopted as a pub name in England in the Middle Ages and many of these still survive.
The term bird in hand must have been known in the USA by 1734, as that is the date when a small town in Pennsylvania was founded with that name.
(資料來源：The Phrase Finder)