Fox hunting, as Oscar Wilde characterised it, was the unspeakable in pursuit of the uneatable.
How, then, to characterise IAG's as-yet unrequited moves for low-cost rival Norwegian?
The incautious in pursuit of the unprofitable, perhaps? Or, if you were being charitable to both parties, the undaunted in pursuit of the unproven.
Norwegian has been heralded as the bright new thing in the market, having revived the long-haul, low-cost concept first pioneered by Sir Freddie Laker. But while the carrier's short-haul business appears robust, questions remain about the state of its transatlantic operation.
Norwegian's most recent financial results showed EBIT losses deepening markedly over the same period a year earlier, while its net loss only improved thanks to the reclassification of a financial investment.
Those figures came on top of a hefty operating loss of NKr2 billion ($256 million) in 2017. In addition, the quarterly accounts raised a warning flag over the rising cost of fuel.
However, the airline's chief executive Bjørn Kjos noted that despite the fact that the Boeing 787 fleet had doubled, it was still filling the aircraft, achieving a load factor of around 85%.
That said, lower fares and longer sector lengths - the flip-side of a move into long-haul - drove down yields and unit revenue.
And a number of recent route suspensions can also be seen in one of two ways: either they are prudent management on the part of the airline - weeding out underperforming services before they become a drain on resources - or they are a sign that its model of flying to certain second- or third-tier US airports is not working.
Norwegian has now rejected two offers from IAG, arguing that they undervalued the airline and its prospects. Kjos says the carrier has received interest from other parties since IAG's intentions became clear; Lufthansa has remained reluctant to discuss whether it is weighing up an investment in its Scandinavian rival.
In a presentation to shareholders, the carrier says that it is now entering a period where it will "start to harvest from its investments".
That does not appear to be a view shared by IAG, with chief executive Willie Walsh warning darkly that, in his view, Norwegian does not have the ability to execute its growth strategy as a standalone operator.
Now, there may be the unmistakable aroma of sour grapes about Walsh's statement, but he would not be the first to cast doubt on Norwegian's ambitious expansion plans and the huge number of aircraft it has on order.
IAG has not set out the reasons for its pursuit of Norwegian, but evidently sees value there - in contrast to the indifference it has shown to Alitalia, for example - despite the financial challenges.
Level, IAG's competitive response to the low-cost, long-haul challenge, has just been assigned additional aircraft; a bolt-on acquisition could be a simple way to further accelerate growth. Equally, Walsh's motive may be to take out, rather than take over, a growing competitive threat.
From Norwegian’s perspective, having a deep-pocketed parent could help a market disruptor avoid any disruption of its own.