Once a thing has been done, however difficult or dangerous it may be, it can
be done again. Take, for example, the example, the exploration of space. On
April 12th, 1961, Major Gagarin of the USSR circled the earth in Vostok I; on
May 5th of the same year Commander Shepherd of the USA attained a height of
117 miles in a space capsule; and on August 6th Major Titov made seventeen
orbits of the earth in Vostok II.