And if diplomacy is the art of finding shared interests and instincts, particularly if one or the other or both might be in short supply, the way Downing Street and the White House described this first conversation since the inauguration is a case study in just that: diplomacy.
Sources in London describe the call as “very warm” and “very personal”. It appears the big picture, and getting to know each other, was the aim, rather than policy detail.
It is, of course, on the policy detail that disagreements loiter.
But for now at least there appears to be an effort on both sides to establish a rapport and for each to size the other up – all ahead of a trip to Washington the prime minister is expected to make in the next handful of weeks.
It is convention when two international leaders speak for each side to issue what is known as a “read out” afterwards – how each side interpreted how the call went and what was discussed.
