Damn your principles, counselled Disraeli, stick to your party.
But what happens when your party won't stick to you?
Two candidates have departed from their party's favours - one Conservative, one Liberal Democrat - in rather different circumstances.
Hugh O' Donnell has chosen to quit the Liberal Democrats to stand as an independent, arguing that his party now prefers to quash dissent rather than adhere to fundamental beliefs.
Malcolm Macaskill was stood down by the Tories after endorsement was withdrawn by the party's candidates selection board.
He was top of the list in Glasgow and hence, potentially, set for a seat.
Each case is damaging to the party concerned.
Political leaders like to project a sense of unity, of contented lieges. These cases, in their different ways, run counter to that depiction.
The extent of the damage depends largely upon the containment exercise. Can the parties close the issues down? Will others rally to support the disquieted and departing?
Mr O'Donnell has been discontented, indeed semi-detached, for some time, since before the formation of the UK coalition.
His departure in this fashion would appear to be planned and calculating rather than whimsical.
The issue for the LibDems is this: can he be dismissed and sidelined as a maverick - or will he be seen as reflecting wider discontent within the party over the consequences of sharing power at Westminster even though his own disquiet partly predates that event?
The Macaskill case is potentially messier. It would appear he has influential - and wealthy - support.
The Tories may stand to lose financial backing from this.
Tory insiders say his endorsement was withdrawn by the all-Scotland candidates board following information which came to light subsequent to his being selected to top the party's list in Glasgow.
He says he is being denied natural justice and an opportunity to state his case.
This follows the disclosure that he has twice faced bankruptcy in the past in his business career.
Mr Macaskill says his business background was made known to the party a decade ago.
But he goes further, linking the handling of his case to suggestions that the party requires wider reform.
Again potentially, that is tapping into subterranean grumbling within the party over the future of the Scottish leadership.
Will that fly as an issue? Or will ranks close?
The immediate rawness of controversy tends to suggest the former.
That applies equally to the LibDem case.
Disraeli's advice, generally followed avidly or reluctantly by those who choose to adhere to parties in the first place, suggests the latter.