「洛陽紙貴」四個字，出於《晉書》卷九十二《文苑·左思傳》：「於是豪貴之家競相傳寫，洛陽為之紙貴。」說的是左思《三都賦》寫成以後的事。本篇用兩頁：《晉書》的左思傳，和《世說新語·文學》裡的同一件事——後者更短，角色與次序也不同。兩頁都不給紙價、不給抄寫工錢；本文只寫這兩頁寫到的。
一、寫賦的十年
左思，字太沖，齊國臨淄人，「家世儒學」。傳裡先寫他不成器：「思小學鍾、胡書及鼓琴，並不成。」父親對朋友說「思所曉解，不及我少時」，他聽了「感激勤學」，又「兼善陰陽之術」。人「貌寢，口訥，而辭藻壯麗。不好交遊，惟以閒居為事」。他先作《齊都賦》，「一年乃成」。
然後是《三都賦》。「復欲賦三都，會妹芬入宮，移家京師，乃詣著作郎張載，訪岷邛之事。遂構思十年，門庭籓溷，皆著筆紙，遇得一句，即便疏之。」——門、庭、籬、廁都放著筆紙，想到一句就記下來。又「自以所見不博，求為秘書郎」。這些是傳裡給的全部寫作情形：沒有講他讀了多少書、訪了多少人，也沒有講他改了幾稿。
二、賦成之後
賦寫成，並不馬上有人看重：「及賦成，時人未之重。思自以其作不謝班張，恐以人廢言。」他自認不比班固、張衡差，怕的是人微言輕。於是去找「有高譽」的安定皇甫謐，「思造而示之。謐稱善，為其賦序」。此後張載注《魏都》，劉逵注《吳》《蜀》並作序，陳留衛權又作《略解》。劉逵序裡有一句說得直白：「世咸貴遠而賤近，莫肯用心於明物。」再後來，司空張華見了嘆道：「班張之流也。使讀之者盡而有餘，久而更新。」
緊接著就是那一句：「於是豪貴之家競相傳寫，洛陽為之紙貴。」這是史書的敘述，不是左思自己的話；「傳寫」的是「豪貴之家」，「貴」的是洛陽的紙。傳裡到這裡就轉了，接下來寫的是陸機。
《世說新語》的版本不同：「左太沖作《三都賦》初成，時人互有譏訾，思意不愜。後示張公。張曰：『此二《京》可三，然君文未重於世，宜以經高名之士。』思乃詢求於皇甫謐。謐見之嗟嘆，遂為作敘。於是先相非貳者，莫不斂衽讚述焉。」——張華在這裡出主意，次序是「先示張公」，再由他去找皇甫謐；《晉書》裡張華是賦成、作序作注之後才「見而嘆」的。兩說並列，不合併。
三、紙貴：原文與沒有的數字
「洛陽為之紙貴」是一句判斷，不是一個數目。兩頁都沒有給紙的價錢、漲了多少倍、抄一部要多少紙、傳寫的有多少家——本文也不補。能說的只有原文給的：左思的賦寫成了，名家作了序與注，張華給了評語，然後「豪貴之家競相傳寫」。紙為什麼貴、貴到幾分，書裡沒有寫。
傳裡還有一段反襯。陸機初到洛陽，「欲為此賦，聞思作之，撫掌而笑」，寫信給弟弟陸雲說：「此間有傖父，欲作《三都賦》，須其成，當以覆酒甕耳。」——等他真讀到，「機絕歎伏，以為不能加也，遂輟筆焉」。從「覆酒甕」到「輟筆」，這段評價的轉變，也寫在傳裡。
四、世說裡的另一次「紙貴」
《世說新語·文學》還記了另一次：「庾仲初作《揚都賦》成，以呈庾亮；亮以親族之懷，大為其名價云：『可三二京，四三都。』於此人人競寫，都下紙為之貴。」——同樣是名人一句評語，帶來一陣搶抄，紙也跟著貴。但這一段後面還有謝太傅一句：「不得爾。此是屋下架屋耳！事事擬學，而不免儉狹。」兩次「紙貴」並排，一次有人捧，一次有人拆。
五、兩頁不給的
兩頁都不給：《三都賦》的全文與字數、抄本的形制、紙的產地與價錢、傳寫者的身分。也不給對這篇賦的「文學價值」判斷——兩頁裡只有幾個人的話：皇甫謐稱善、劉逵作序、張華嘆為「班張之流」、陸機歎伏、謝安評《揚都賦》「屋下架屋」，各是各人的話，本文逐條標出說話人。
「洛陽紙貴」後來成為成語，那是後人的概括；《晉書》原文只有「洛陽為之紙貴」這一句，兩頁都沒有把它當成語用。本文不寫「文學價值」「文化傳播」一類的通論，也不把這件事講成紙張史；只寫一個賦、幾個人、一句紙貴，以及書裡沒有給的那些數字。
延伸閱讀：求雨：董仲舒的儀式與王充的質疑 · 王亥：被有易氏殺掉的商先祖 · 賦詩：七個人，七首詩，一句判詞
參考來源與延伸閱讀
- 《晋书》卷九十二·文苑·左思传（唐房玄龄等撰；维基文库本，页面白文无注，未与中华书局点校本复核） — The full life: Zuo Si of Linzi, of a family of scholars, who failed at writing and at the qin, was mocked by his father, and turned to study; 'he made the Rhapsody on the Qi Capital, which took a year'; then, wishing to write on the three capitals, he moved to the capital when his sister entered the palace, questioned the works officer Zhang Zai about Min and Qiong, and 'pondered for ten years, with paper and brush placed at his gate, courtyard, fence and privy, writing down any line as soon as it came'; thinking his knowledge not broad enough, he asked to be made a secretary; when the rhapsody was finished 'his contemporaries did not value it', so he showed it to Huangfu Mi, who praised it and wrote a preface; Zhang Zai annotated the Wei capital, Liu Kui the Wu and Shu with a preface, and Wei Quan added a brief explanation; Zhang Hua sighed that it was 'of the company of Ban Gu and Zhang Heng'; 'thereupon the rich and noble houses competed in copying it, and Luoyang became expensive in paper'. Lu Ji, who had meant to write such a rhapsody himself, laughed at the news and wrote to his brother that the man would end by covering a wine jar with it, and after reading the work 'was utterly astonished and gave up his brush'.
- 《世说新语·文学》（南朝宋刘义庆撰，刘孝标注；维基文库本，页面白文夹注，未与中华书局点校本复核） — A shorter account of the same affair: when the Rhapsody on the Three Capitals was first finished 'contemporaries mocked and criticised it in turn, and Si was displeased'; he showed it to 'Master Zhang' — Zhang Hua — who said it could stand as a third to the two Han capitals, but that 'your writing is not yet weighty in the world; you should let it pass through a man of high name'; Zuo Si then sought out Huangfu Mi, who sighed over it and wrote the preface, after which 'those who had opposed it all straightened their robes and praised it'. The same chapter has a second paper-price story: Yu Chan's Rhapsody on the Yang Capital, presented to Yu Liang, who talked up its value as 'a third to the two capitals, a fourth to the three capitals', whereupon 'everyone competed to copy it and the paper of the capital became expensive' — and Xie An's retort that it was only 'building a house under a house'.
