第 19 条 · 自然数列与负数列

In the same manner, therefore, as positive numbers are incontestably greater than nothing, negative numbers are less than nothing.

同样，正数无疑大于零，负数则小于零。

Now, we obtain positive numbers by adding 1 to 0, that is to say, 1 to nothing; and by continuing always to increase thus from unity.

我们从 0 开始加 1，就得到正数；再从 1 起不断这样增加。

This is the origin of the series of numbers called natural numbers; the following being the leading terms of this series: 0, +1, +2, +3, +4, +5, +6, +7, +8, +9, +10, and so on to infinity.

这就是称为自然数的数列的来源；它开头的项是：0、+1、+2、+3、+4、+5、+6、+7、+8、+9、+10，并且这样一直到无穷。

But if, instead of continuing this series by successive additions, we continued it in the opposite direction, by perpetually subtracting unity, we should have the following series of negative numbers: 0, -1, -2, -3, -4, -5, -6, -7, -8, -9, -10, and so on to infinity.

但如果我们不靠连续相加来延伸这个数列，而是朝相反方向不断减去 1，就得到负数列：0、-1、-2、-3、-4、-5、-6、-7、-8、-9、-10，并且这样一直到无穷。