英文原文："Individuals differ from one another in their ability to understand complex ideas, to adapt effectively to the environment, to learn from experience, to engage in various forms of reasoning, to overcome obstacles by taking thought. Although these individual differences can be substantial, they are never entirely consistent: a given person's intellectual performance will vary on different occasions, in different domains, as judged by different criteria. Concepts of "intelligence" are attempts to clarify and organize this complex set of phenomena. Although considerable clarity has been achieved in some areas, no such conceptualization has yet answered all the important questions, and none commands universal assent. Indeed, when two dozen prominent theorists were recently asked to define intelligence, they gave two dozen, somewhat different, definitions."

粵文翻譯：唔同嘅個體之間喺理解複雜諗頭嘅能力、有效噉適應環境、由經驗嗰度學習、做推理、用思考克服障礙（等方面）上有差異。雖然呢啲個體差異可以好巨大，佢哋（啲個體差異）唔係完全前後一致嘅：是但搵個人，佢嘅智能表現會隨時間、領域、同埋判斷嘅準則而有變化。「智能」呢個概念係對於闡明同組織呢一柞複雜現象嘅嘗試。雖然喺某啲地方（心理學界方面）做咗唔少嘅闡明，但係目前仲未有可以解答嗮所有重要問題嘅概念化，而且冇一個係個個學者都認同嘅。事實係，當早嗰排有兩打重要嘅理論家俾人叫佢哋定義智能嗰陣，佢哋俾咗兩打彼此之間有些少唔同嘅定義出嚟。