No man can fully grasp how far and how fast we have come, but condense, 没有人能够完全明白我们已经走了多远，走得多快，但是如果你愿意，

if you will, the 50,000 years of man's recorded history in a time span of but a half-century. 可以把人类有史以来的5万年浓缩成半个世纪的时间跨度。

Stated in these terms, we know very little about the first 40 years, 在这个时间跨度下，我们对于开始的40年知之甚少，

except at the end of them advanced man had learned to use the skins of animals to cover them. 只知道在这40年的最后人类学会用兽皮遮体。

Then about 10 years ago, under this standard, man emerged from his caves to construct other kinds of shelter. 然后，大约10年前，根据这一标准，人类走出洞穴，开始建造其他类型的住房。

Only five years ago man learned to write and use a cart with wheels. Christianity began less than two years ago. 只有5年前的人类才学会了写字和使用有轮子的车辆。基督教出现还不到两年。

The printing press came this year, and then less than two months ago, 今年出现看印刷机，不到两个月前，

during this whole 50-year span of human history, the steam engine provided a new source of power. 在人类历史的整个50年跨度中，蒸汽机提供了一种新能源。

Newton explored the meaning of gravity. Last month electric lights and telephones and automobiles¹ and airplanes became available. 牛顿研究出重力的意义。上个月电灯、电话和汽车、飞机都可以使用了。

Only last week did we develop penicillin² and television and nuclear power, 仅仅上周，我们就发明了青霉素，电视机和核能，

and now if America's new spacecraft³ succeeds in reaching Venus, we will have literally⁴ reached the stars before midnight tonight. 而现在如果美国飞往金星的新的宇宙飞船成功，我们真能在今晚午夜之前到达星星之上。

This is a breathtaking pace, and such a pace cannot help but create new ills as it dispels⁵ old, new ignorance, new problems, new dangers. 这是激动人心的一步，但这一步在驱除旧弊病的同时，也会产生新的弊病、新的无知、新的问题与新的危险。

Surely the opening vistas⁶ of space promise high costs and hardships, as well as high reward. 航天事业战线的远景当然是成本高，但是回报也很丰厚。