「我們大膽地假設，在一些溫暖的小池塘裡，充滿著各種氨氣（ammonia）、磷鹽（phosphoric salts），以及光、熱或電流等，使蛋白質化合物得以從化學反應中產生，並準備進行更複雜的變化—雖然蛋白質在現今的環境通常會被立即吞噬或吸收，則生物形成時的環境狀況應該與現今大不相同。」
查爾斯‧達爾文於1871年致Joseph Dalton Hooker的一封信件中提出著名的「溫暖小池塘」假設
"But if ( and oh what a big if ) we could conceive in some warm little pond with all sorts of ammonia and phosphoric salts, - light, heat, electricity &c. present, that a protein compound was chemically formed, ready to undergo still more complex changes, at the present day such matter would be instantly devoured, or absorbed, which would not have been the case before living creatures were formed."
From a letter written by Charles Darwin to Joseph Hooker in 1871 which included some of
his speculations on the spontaneous generation of life in some 'warm little pond'.
