作者開篇又對比了一下農(nóng)業(yè)與工業(yè)的差異 —— 而這就帶出了一個(gè)重要的概念：

傳統(tǒng)的生產(chǎn)分析著重于農(nóng)業(yè)。

馬歇爾開始重視工業(yè)。

其中最重要的一點(diǎn)，是工業(yè)生產(chǎn)加上了“上頭成本”（overhead costs，馬歇爾稱之為supplementary costs）。

什么是上頭成本（overhead costs）？

字典把overhead costs譯作“經(jīng)常性支出”，不對，無以名之，直譯為“上頭成本”最恰當(dāng)。

上頭成本必定要在作了生產(chǎn)投資，開了檔，才可以存在。這些成本是指開始經(jīng)營后，有些費(fèi)用不生產(chǎn)也要支付。

上頭成本還有另外一個(gè)定義，那是指一家生產(chǎn)企業(yè)若出產(chǎn)幾種或多種產(chǎn)品時(shí)，某些成本（上頭成本）不能在不同的產(chǎn)品上攤分。

上頭成本與直接成本之間通常有一片灰色地帶。以一間酒家而論。。。侍應(yīng)、廚師等工資，可以在某種程度上以生意的多少來調(diào)整，屬于灰色地帶。這是吹毛求疵的問題，不重要。

那看看眾包大辭海的定義呢？

In business,?overhead?or?overhead expense?refers to an ongoing?expense?of operating a business. Overheads are the?expenditure?which cannot be conveniently traced to or identified with any particular revenue unit, unlike operating expenses such as raw material and labor. Therefore, overheads cannot be immediately associated with the products or services being offered, thus do not directly generate profits. However, overheads are still vital to business operations as they provide critical support for the business to carry out profit making activities. For example, overhead costs such as the rent for a factory allows workers to manufacture products which can then be sold for a profit. Such expenses are incurred for output generally and not for particular work order; e.g., wages paid to watch and ward staff, heating and lighting expenses of factory, etc. Overheads are also a very important cost element along with direct materials and direct labor.

Overheads are often related to?accounting?concepts such as?fixed costs?and?indirect costs.

Overhead expenses are all costs on the income statement except for direct labor, direct materials, and direct expenses. Overhead expenses include accounting fees,?advertising,?insurance, interest, legal fees, labor burden,?rent, repairs, supplies, taxes, telephone bills, travel expenditures, and utilities.

這個(gè)定義中講了三個(gè)維度，其中：

- 第一段，和作者提到的兩個(gè)定義是一致的，“人工”、“原材料”等可以“直接”跟蹤到某營收單元之外的，就是overhead (expense)

- 第二段，從會計(jì)角度，overhead一般指的是fixed costs / indirect costs —— 但是經(jīng)濟(jì)學(xué)上三者概念可以說是一致的

- 第三段，這就是經(jīng)濟(jì)學(xué)和會計(jì)學(xué)的分野了，眾包大辭海中列舉的這些，在經(jīng)濟(jì)學(xué)上也可以稱之為“成本”；但是如折舊、攤銷等過去投入的分?jǐn)偅策M(jìn)入income statement，就不是了 —— 作者也進(jìn)行了解釋：

重要的是上述的成本不一定是成本。有兩個(gè)原因：

其一。。。歷史成本不是成本。

這個(gè)當(dāng)然，經(jīng)濟(jì)學(xué)的選擇，是基于當(dāng)下的選擇，是向前看。

其二。。。在組合生產(chǎn)要素時(shí)，你可能簽了好些合約，作了承諾，不能反悔。不能更改的支出，因?yàn)闆]有選擇而變?yōu)椴皇浅杀尽?/i>

這里有兩點(diǎn)：

- 作者可能指的是預(yù)付之類，所有的預(yù)付也是有違約代價(jià)的；

- 當(dāng)然，另外一個(gè)角度是基于反事實(shí)的角度 —— 站在此時(shí)此刻的時(shí)間點(diǎn)，將反悔與不反悔的所有收益代價(jià)核算一遍，比較一下，自然也清楚了。