14 INTRODUCTORYand after the Nazi period attests. When he spoke or wrote of justice and liberty
for others, called the Jews his brothers, or grieved for the heroes of the Warsaw
ghetto, he did so as a man of feeling at least as much as a man of thought. That,
having thus spoken and thus felt, he would want to return to the purity and safety
of the world of ideas is not an entirely uncommon desire. Truly remarkable, how-
ever, was his gift to effect the return to that world without emotional effort. He
had no need to push the everyday world away from him. He just stepped out of
it whenever he wished. It is therefore not surprising either that (as he wrote
shortly before his death) he twice failed rather disgracefully in marriage or that
in his life there is an absence of figures with whom he identified—with the excep-
tion, perhaps, of Newton.
It seems to me that, when in midlife Einstein wrote of 'The wonderful events
which the great Newton experienced in his young days. .. Nature to him was an
open book. ... In one person he combined the experimenter, the theorist, the
mechanic, and, not least, the artist in exposition.. .. He stands before us strong,
certain, and alone: his joy in creation and his minute precision are evident in every
word and every figure .. .' [E8], he described his own ideals, the desire for ful-
fillment not just as a theorist but also as an experimental physicist. (In the second
respect, he, of course, never matched Newton.) Earlier he had written that New-
ton 'deserves our deep veneration' for his achievements, and that Newton's own
awareness of the weaknesses of his own theories 'has always excited my reverent
admiration' [E9] (these weaknesses included the action of forces at a distance,
which, Newton noted, was not to be taken as an ultimate explanation).
'Fortunate Newton, happy childhood of Science!' [E8]. When Einstein wrote
these opening words in the introduction to a new printing of Newton's Opticks,
he had especially in mind that Newton's famous dictum 'hypotheses non fingo,'
I frame no hypotheses, expressed a scientific style of the past. Elsewhere Einstein
was quite explicit on this issue:
We now know that science cannot grow out of empiricism alone, that in the
constructions of science we need to use free invention which only a posteriori
can be confronted with experience as to its usefulness. This fact could elude
earlier generations, to whom theoretical creation seemed to grow inductively out
of empiricism without the creative influence of a free construction of concepts.
The more primitive the status of science is the more readily can the scientist
live under the illusion that he is a pure empiricist. In the nineteenth century,
many still believed that Newton's fundamental rule 'hypotheses non fingo'
should underlie all healthy natural science. [E10]
Einstein again expressed his view that the scientific method had moved on in
words only he could have written:
Newton, forgive me; you found the only way which in your age was just about
possible for a man with the highest powers of thought and creativity. The con-
cepts which you created are guiding our thinking in physics even today,