Governments usually lose by-elections. Sometimes such defeats can be a harbinger of doom for the following general elections. Sometimes, however, they can mean very little in the wider scheme of things.
The ones most frequently cited are the two by-elections in Cork City and Cork North East when Fianna Fáil received a drubbing, thus hastening the resignation of Jack Lynch.
Then, Fine Gael's Liam Burke defeated Fianna Fail's John Dennehy after a brilliant campaign to fill the vacancy caused by the death of Labour's Patrick Kerrigan.
Much more seriously from Mr Lynch's point of view, Fine Gael's Myra Barry was brought home victorious on the same day in the race to replace Fianna Fáil's Seán Brosnan.
However, 23 years have passed since a government won a by-election, when Noel Treacy, now the Minister of State in the Department of Foreign Affairs, filled the shoes of the late Fianna Fáil TD, John Callanan.
One of the most extraordinary by-election campaigns, replete with political strokes, occurred just a few weeks earlier in Dublin West when Fine Gael's Liam Skelly replaced Fine Gael's Richard Burke.
The by-election was caused by a stroke when Fianna Fáil's Charles J. Haughey, who was in need of an extra TD, tempted Mr Burke with the offer of Ireland's place on the European Commission.
Satisfied, Mr Burke accepted the post, though Mr Haughey's plan went awry when Fine Gael's Liam Skelly won the favour of locals over Fianna Fáil's candidate, Eileen Lemass.
The by-election has entered legend because it was the one where disgraced, and now imprisoned ex-cabinet minister, Ray Burke, ordered trees to be planted in a housing estate in the constituency.
Disgusted by the locals' decision not to back Fianna Fáil, Burke went out immediately after the voting and ordered all the trees to be pulled up and removed.
