There's no single interest rate in the economy.

经济中没有单一的利率。

To evolutionists may be left the processes of evolution; to historians the single interest is the law of reaction between force and force — between mind and nature — the law of progress.

进化论者可能会留给进化过程；对历史学家来说，唯一的兴趣是力与力之间——思想与自然之间——进步的规律。

But in any case, the whole college course will be unified and dominated by a single interest, a single purpose — that of so understanding human life as to be ready and equipped for the practice of it.

但无论如何，整个大学课程将统一并由一个单一的兴趣、一个单一的目的所支配——理解人类生活，以便为实践它做好准备和装备。