It is probably true quite generally that in the history of human
thinking the most fruitful developments frequently take place at
those points where two different lines of thought meet. These lines
may have roots in quite different parts of human culture, in different
times or different cultural environments or different religious tra-
ditions: hence if they actually meet, that is, if they are at least so
much related to each other that a real interaction can take place,
then one may hope that new and interesting developments may
follow.

WERNER HEISENBERG ¹

When, in the spring of 1669, the Trinity fellow Francis
Aston was preparing to leave on a European tour, he
wrote to his friend Isaac Newton asking for his advice
on how best to conduct himself and what to look out for on his
travels. This is surprising, since Newton had never travelled abroad
and had only recently made his first trip to London. But it illustrates
the high esteem in which Newton was held by his colleagues so early
in his career, even in connection with matters outside his area of
expertise. More significant still is Newton's reply to Aston's letter,
for, as well as asking his friend to gather alchemical information for
him and to attempt to track down the famous alchemist Giuseppe
Francesco Borri, then living in Holland, Newton went on to offer a
long list of dos and don'ts as though he were a seasoned globe-trotter.
These included the recommendation:

If you be affronted, it is better in a foreign country to pass it
by in silence or with jest though with some dishonour than to
endeavour revenge; for in the first case your credit is none the
worse when you return into England or come into other com-

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