In the earlier epochs of history, we find almosteverywhere a complicated arrangement of society into various, orders, a manifold gradation of social rank. In ancient Rome we have patricians, knights, plebeians,slaves; in the Middle Ages, feudal lords, vassals, guild-masters, journeymen, apprentices, serfs; in almost all of these classes, again, subordinate gradations.
The modern bourgeois society that has sprouted from the ruins of feudal society has not done away with clash antagonisms. It has but established new classes, new conditions of oppression, new forms of struggle in place of the old ones. Our epoch, the epoch of the bourgeoisie,possesses, however, this distinctive feature: it has simplified the class antagonisms: Society as a whole is more and more splitting up into two great hostile camps,into two great classes, directly facing each other: Bourgeoisie and Proletariat.
From the serfs of the Middle Ages sprang the chartered burghers of the earliest towns. From these burgesses the first elements of the bourgeoisie were developed.
The discovery of America, the rounding of the Cape, opened up fresh ground for the rising bourgeoisie. The East-Indian and Chinese markets, the colonization of America,trade with the colonies, the increase in the means of exchange and in commodities generally, gave to commerce,to navigation, to industry, an impulse never before known,and thereby, to the revolutionary element in the tottering feudal society, a rapid development.
The feudal system of industry, under which industrial production was monopolize by closed guilds, now no longer sufficed for the growing wants of the new markets. The manufacturing system took its place. The guild-masters were pushed on one side by the manufacturing middle class; division of labor between the different corporate guilds vanished in the face of division of labor in each single workshop.
Meantime the markets kept ever Rowing, the demand ever rising. Even manufacture no longer sufficed. Thereupon, steam and machinery revolutionized industrial production.The place of manufacture was taken by the giant, Modern Industry, the place of the industrial middle class, byindustrial millionaires, the leaders of whole industrial armies, the modem bourgeois.
无自由民和奴隶，贵族和平民，地主和农奴，行会师傅和帮工，简短些说，压迫者和被压迫者，始终处于相互对抗的地位，进行不断的，有时隐蔽，有时公开的斗争，而每一次斗争的结局，不是整个社会受到革命改造，就是斗争的各阶级同归于尽。
在过去的各个历史时代，我们几乎到处都可以看到社会完全划分为各个不同的等级，可以看到由各种不同的社会地位构成的整个阶梯。在古代的罗马，有贵族、骑士、平民和奴隶；在中世纪，有封建领主、陪臣、行会师傅、帮工和农奴，并且几乎在每一个阶级内部，又有各种特殊的等第。
从灭亡了的封建社会里产生出来的现代资产阶级社会，并没有消灭阶级矛盾。它不过用新的阶级、新的压迫条件、新的斗争形式代替了旧的罢了。但是，现今的这个时代，即资产阶级时代，却有一个特点，就是它使阶级矛盾简单化了：社会日益分裂为两大敌对的阵营，即分裂为两大相互直接对立的阶级——资产阶级和无产阶级。从中世纪的农奴中间产生了初期城市的自由居民；从这个市民等级中间发展出最初的资产阶级分子。
美洲和环绕非洲的航路的发现，给新兴的资产阶级开辟了新的活动场所。东印度和中国的市场，美洲的殖民化，对殖民地的贸易，交换资料和一般商品的增加，给予了商业、航海业和工业空前未有的刺激，因而也就促进了崩溃的封建社会内部所产生的革命因素的迅速发展。
以前封建的或者行会的工业组织已经不能再满足随着新市场的扩大而增加的需求了。于是，就有工场手工业取而代之。行会师傅被工业的中层等级排挤掉了；各个同业公会间的分工也就从此消失，由各个作坊内部的分工所代替了。
但是，市场总是在扩大，需求总是在增加。工场手工业也不能再满足这种需求了。于是，蒸汽和机器就引起了工业中的革命。现代的大工业代替了工场手工业；工业中的百万富翁，一批批产业军的统领，即现代的资产者，代替了工业的中层等级。