Brothers and sisters
Isn't it wholly refreshing to witness a politician disdaining the customary euphemisms when announcing a decision about his future?
He doesn's say he intends to spend more time with his family or his constituency or his dog.
Rather, he says that the challenge requires certain qualities which he does not possess.
Hang on just a second, though, before awarding him the Order of Merit (Second Class) for collegiate self-deprecation.
The influential backbench MP also indicates that he has neither the time nor the inclination to spend half the week preparing to knock lumps out of his opponent (or, in these coalesced days, opponents) in the Commons.
In other words, the job is wrong for him - rather than perhaps the other way round.
Right to rule
Mr Cruddas, a thoughtful figure, says two further things. He wants to contribute in some way to reshaping the Labour Party. Secondly, he wants the leadership contest to be prolonged: a "battle of ideas."
What impact might all this have upon the Scottish Labour Party - or, more precisely, the semi-devolved Labour Party in Scotland?
Despite Wendy Alexander's past insolence, I am not convinced that the Labour Party in Scotland is entirely an idea-free zone.
Certainly, there is a substantial segment of the party which has not completely liberated itself from the concept that it has a natural right to rule.
But the hustings for the Holyrood leader were lively and combative without being confrontational.
No, it's not the "ideas" bit which would trouble Scottish Labour overmuch. Rather it's the suggestion of a "battle".
Labour in Scotland cannot afford a leadership contest which is too prolonged or too bloody. It does not have the breathing space - with Holyrood elections due next May.
On the other hand, the party in Scotland may be hoping that a sensible, well-argued debate might help energise the comrades.
A discussion among sisters and brothers. Brothers being particularly apposite.