段一：前言與紅白雙龍之戰

梅林的預言

《梅林的預言》開篇是傑佛瑞·蒙茅斯寫給林肯主教亞歷山大的獻辭與書信，交代本書由來；接著借不列顛王沃提根的故事，引出梅林以紅白雙龍解夢的著名場景。以下為公有領域英譯（Sebastian Evans 1904 譯）原文節錄。

原文（公有領域英譯）

CHAPTER I — OF THE PROPHECIES OF MERLIN

I had not come so far as this place of my history, when by reason of the much talk that was made about Merlin my contemporaries did on every side press me to make public an edition of his prophecies, and more especially Alexander, Bishop of Lincoln, a man of the highest piety and wisdom. … Wherefore, for that he it was whom I did most earnestly desire to please above all other, I did translate the prophecies and did send them unto him along with a letter unto this effect.

CHAPTER II

"The affection I bear unto thy nobility, Alexander, Prelate of Lincoln, hath compelled me to translate the Prophecies of Merlin out of the British into Latin before I had made an end of the History I had begun as concerning the acts of the British Kings … I have set my rustic reed to the writing of these little books, and have interpreted for thee this unknown language."

CHAPTER III

Accordingly, while Vortigern, King of the Britons, was yet seated upon the bank of the pool that had been drained, forth issued the two dragons, whereof the one was white and the other red. And when the one had drawn anigh unto the other, they grappled together in baleful combat and breathed forth fire as they panted. But presently the white dragon did prevail, and drave the red dragon unto the verge of the lake. But he, grieving to be thus driven forth, fell fiercely again upon the white one, and forced him to draw back. And whilst that they were fighting on this wise, the King bade Ambrosius Merlin declare what this battle of the dragons did portend. Thereupon he straightway burst into tears, and drawing in the breath of prophecy, spake, saying;

白話解說

呢段講咩？ 傑佛瑞一開頭就話：因為好多人（尤其林肯主教亞歷山大）成日追住佢，叫佢公開梅林嘅預言，於是佢就將梅林預言由「不列顛語」譯做拉丁文，連同一封信寄畀主教。即係話，本書係佢應人要求先寫嘅——呢個「應命而作」嘅開場，本身係當時好常見嘅文學客套。

雙龍之戰點嚟？ 跟住佢借《不列顛諸王史》入面一個舊橋段：王沃提根喺一個排乾咗嘅池塘邊，見到一紅一白兩條龍大打出手，互相噴火。白龍先贏，將紅龍迫到湖邊；紅龍唔忿氣，反擊又迫返白龍退後。王就叫「安布羅修斯·梅林」講吓呢場龍戰代表乜嘢。梅林即刻喊出嚟，然後「吸一口預言之氣」，開金口。

點解叫「安布羅修斯·梅林」？ 呢度將兩位古人溝埋一齊。安布羅修斯·奧雷利安（Ambrosius Aurelianus）係吉爾達斯、內尼烏斯等古史家提到嘅羅馬—不列顛領袖；學者認為傑佛瑞係有意將佢同梅林混為一體，製造一個「先知」角色。即係話，梅林呢個名，好可能係傑佛瑞嘅文學發明，唔係真有其人。

關於「梅林」呢個名： 佢由威爾士文「Myrddin」演變出嚟。威爾士學者 Rachel Bromwich 指，將中間個「dd」音變成「l」好古怪；法國學者 Gaston Paris 就解釋，係因為法文「merde」（粗口）諧音難聽，所以改咗。即係話，連個名本身都有段故。

客觀睇： 呢段純粹係全書嘅「入場」——交代作者點解要寫、梅林係乜水、雙龍場景點解。未有正式預言內容，但已經鋪好「紅=不列顛人、白=撒克遜人」呢個最重要嘅象徵。