兩個數字放在一起，差別很大。一個說國家的馬：「馬至二百餘萬匹。」一個說一匹馬：「頭為王，欲得方；目為丞相，欲得光；脊為將軍，欲得強；腹脅為城郭，欲得張；四下為令，欲得長。」前一句是史書裡的牧地帳，後一句是農書裡的相馬口訣。
河西牧地
《魏書·食貨志》只用兩句：「世祖之平統萬，定秦隴，以河西水草善，乃以為牧地。畜產滋息，馬至二百餘萬匹，橐駝將半之，牛羊則無數。」——平定統萬、秦隴之後，看中河西的水草，把它劃為牧地；牲畜繁殖，馬到二百餘萬匹，駱駝將近一半，牛羊多得數不清。這是據記載的官方說法，不是今天的普查資料。
同一段還有後話：高祖即位後，「復以河陽為牧場，恆置戎馬十萬匹，以擬京師軍警之備」；每年「自河西徙牧於并州，以漸南轉」，為的是讓馬「習水土而無死傷」；於是「河西之牧彌滋矣」。最後一句是衰敗：「正光以後，天下喪亂，遂為群寇所盜掠焉。」——繁殖與掠奪都寫在同一段裡。
讀這幾個數要注意三件事：一是「二百餘萬」只是河西牧地，不是全國馬數；二是駱駝「將半之」、牛羊「無數」都是概數，數量級和馬不同；三是「恆置戎馬十萬匹」是河陽的常備軍馬，和河西的畜產總數不是同一種計算基準，不能相加。至於「河西」具體指哪一片、邊界在哪，學界有爭論，這篇不劃地圖。
牧場的帳
從這條記載還能讀出牧場的性質：它是官有的，所以史官按畜產記帳；它按「匹」數馬、按「將半之」數駱駝、按「無數」數牛羊，可見不同牲畜的登記精細程度不同；它「歲徙牧於并州」，可見這不是圍起來的固定馬場，而是隨水草移動的牧地——「以漸南轉」是為了讓馬換水土時不至於死傷。
不能從這條記載推出的是：某一年的精確在養頭數（「滋息」是一個過程，不是某年的普查）；平均每戶有幾匹馬（沒有對應的戶口資料）；全國的馬政（這只是河西一處，另有河陽）。數字本身也要加上「據記載」三個字——這是史官寫的數，不是送交朝廷的實收帳。
一匹馬怎麼養
《齊民要術》卷第六專講養牛馬驢騾，開頭一句就把原則說了：「服牛乘馬，量其力能；寒溫飲飼，適其天性：如不肥充繁息者，未之有也。」——按力氣用，按天性餵；照這樣做還不肥壯繁殖的，沒有。然後是相馬的口訣：頭要方、目要光、脊要強、腹脅要張、四腿要長；「凡相馬之法，先除『三羸』、『五駑』，乃相其餘」——三羸是大頭小頸、弱脊大腹、小脛大蹄；五駑是大頭緩耳、長頸不折、短上長下、大髂短脅、淺髖薄髀。先把這些毛病剔掉，再評其餘。
餵法更具體：「飲食之節：食有『三芻』，飲有『三時』。」三芻是惡芻、中芻、善芻——「善謂飢時與惡芻，飽時與善芻，引之令食，食常飽，則無不肥」；三時是「朝飲，少之；晝飲，則胸饜水；暮，極飲之」。還有「十日一放，令其陸梁舒展」，讓馬撒開跑一跑，筋骨才硬實。
連治病都有方子：馬患喉痺將死，「纏刀子露鋒刃一寸，刺咽喉，令潰破即愈」；黑汗，取馬屎與亂髮燒煙燻鼻；中熱，煮大豆與熱飯餵；汗凌，好酒浸豆豉絞汁灌口；疥瘡，雄黃、頭髮用豬脂煎了塗。農書的實用層面，細到這個程度。
兩個層面
官牧與農書是兩層材料。一個記國家牧場的畜產，一個記一匹馬的相法與療法；不能互推：二百餘萬匹推不出「每戶有馬」，農書也證明不了牧場規模。一個數字要加上「據記載」，一套手藝則可以直接照做——這就是兩類文本的差別。
還有一層：馬在這兩頁裡都是「力」與「產」。史書關心的是有多少匹、夠不夠軍用；農書關心的是怎麼相、怎麼餵、怎麼治。前者是國家的帳，後者是牧人的手藝；把兩者放在一起看，才知道「二百餘萬匹」背後，是無數匹具體的馬要過冬、要換水土、要治喉痺。
材料裡沒有的
缺口：牧場的面積與邊界（有爭論，不劃圖）；馬匹每年的增長與死亡數；官牧與民間的比重；馬價；「二百餘萬」的統計方法。兩頁都沒有。所以這篇文章寫的是一段牧地記載加一部農書，不是北魏馬政的全貌。
一個數字，一套手藝：一邊是「馬至二百餘萬匹」，一邊是「頭為王，目為丞相」。前者要加上「據記載」，後者可以直接照做。讀這兩頁，最好把兩種語氣分開——史官在報帳，牧人在教徒弟。
延伸閱讀：方里而井：孟子紙上的一幅田制 · 九州的貢單：《禹貢》與《職方氏》兩份對不上的清單 · 重罪十條：《隋書》裡的一段北齊律
參考來源與延伸閱讀
- 《魏书》卷一百一十·食货志（北齐魏收撰；维基文库本，未与点校本复核） — The register passage, to be quoted as what the history records. After Emperor Shizu pacified Tongwan and settled Qin and Long, 'because the grass and water west of the Yellow River were good, he made it pasture land. The herds multiplied: horses reached more than two million, camels nearly half that, cattle and sheep beyond counting' (以河西水草善，乃以為牧地。畜產滋息，馬至二百餘萬匹，橐駝將半之，牛羊則無數). It then records that under Emperor Gaozu a pasture was also made at Heyang, 'constantly holding a hundred thousand army horses against alarms at the capital', and that every year horses were moved from the western pasture to Bingzhou, gradually southward, 'so that they might grow used to the water and soil and not die'; the western herds then 'multiplied the more'. Finally: after Zhengguang, with the realm in disorder, they were 'stolen and plundered by the various bandits'. The passage gives no boundaries for the pasture, no rate of increase and no price.
- 《齐民要术》卷第六·养牛马驴骡第五十六（北魏贾思勰撰；维基文库本，未与点校本复核） — The practical manual, a different kind of text. It opens: 'Drive oxen and ride horses by measuring their strength; feed and water them warm or cold according to their nature — and if they do not grow fat and multiply, there is no such case' (服牛乘馬，量其力能；寒溫飲飼，適其天性). On judging a horse: 'the head is the king, it should be square; the eye is the chancellor, it should be bright; the spine is the general, it should be strong; the belly and flanks are the city wall, they should be stretched; the four legs are the magistrate, they should be long' (頭為王…四下為令). The method first rejects 'three weaknesses' and 'five jades' (三羸五駑) — a big head with a thin neck, a weak spine with a big belly, thin shins with big hooves; a big head with slack ears, a long neck that does not bend, short above and long below, big hips with short ribs, shallow hips with thin thighs — and judges the rest. On feeding: 'food has three kinds of hay, drink has three times' (食有三芻，飲有三時): bad, middle and good hay, with good hay given when hungry and bad when full; morning drink little, midday drink until the chest is satisfied, evening drink to the full. It also gives remedies: for a swollen throat, a knife blade laid bare an inch and thrust into the throat; for black sweat, burning horse dung and human hair under the nose; for heat, boiled beans and hot rice; for sweat-chill, fermented beans steeped in good wine poured into the mouth; for mange, realgar and hair fried in pig fat.
