To get a full appreciation of what this means we must turn first to some recent human inventions.

要透彻理解这句话的意义，我们应先回顾一下人类最近的几项发明。

for fear the agents of other firms should be able to trace the kind of research they are likely to be undertaking.

他们生怕别的公司的情报人员据此摸到他们可能要从事的某项科研项目。

With the invention of writing, a great advance was made, for knowledge could then be not only communicated but also stored.

随着书写的发明，又迈进了一大步，因为这样一来，知识不仅能交流，而且能储存了。

not as description or reminiscence.

不要靠描述和印象去感觉。

And it should not be forgotten how small those resources are in a poor and backward country.

不应忘记，在一个贫穷落后的国家里，那部分财力是很有限的。

It is best to keep to hot drinks, bottled or canned drinks of well-known brand names----

最好仅饮用开水，名牌瓶装或罐装水