When you're a hammer, everything's a nail.
That's the wisdom of American psychologist Abraham Maslow, who coined the phrase back in 1966 with his law of the instrument theory.
This metaphor helped explain the idea of cognitive bias, which involves over-reliance on a familiar tool or social theory.
Although he died shortly after, Maslow's sage wisdom has been enjoying a renewed relevance on Twitter this week, where people have been using it to describe the behaviour of modern feminists, who believe their latest hot-button issue is sleep - or a lack thereof.
Not the burqa or female genital mutilation. Not even the fact that rape syndicates continue to target young, white girls across the UK. But the idea that men are secretly stealing their rest as a little-known manifestation of sexism. Yep, they really are that narcissistic!
"Ask yourself how much sleep you lose to a man's unconscious sense of entitlement?" journalist Lucy Mangan writes in the new issue of the UK's Stylist magazine. "[It's] a belief so profound it seems natural to feel his time, his rest, his smooth passage through the world is more important than yours." One study apparently found women lose three hours of sleep every night because of their selfish male partners.
Mangan suggests women should resolve this "problem" by giving their boyfriends "a good slap."
Needless to say, there's absolutely no science in the article. Not a single statistic or peer-reviewed paper. No discussion of polysomnography, circadian rhythms, sleep apnoea, night terrors or insomnia. There isn't even reference to a bad dream, which is clearly what modern feminism has become. Or is that a living nightmare?
Either way, here's a long-overdue wake-up call: ladies, we don't think about you 24/7. There is no master plan to oppress you. Or steal your sleep. In fact, we want you to get a full eight hours each night, because that way we'll be guaranteed some welcome respite from the relentless BS which has mushroomed since lockdown began.
Also this week, journalist Helen Coffey wrote in the Independent that men were now "manspreading" while running, thus oppressing women during their daily exercise allowance. "Taking up space in the world seems hardwired for men - but right now, it reeks of selfishness," she declared (without proof, obviously).
Days earlier, Alice Thomson wrote in the Times that, while Covid-19 is primarily killing men, it's women who are worst affected.
"It may be more deadly for men," she claimed. "But it seems to be hurting women in other ways - pushing them back into domesticity just when they thought they'd escaped."
Yep, that's right. Even when the world is supposed to be uniting in the face of a global health crisis, these people can't resist hammering everything like it's a damn nail.
Quite frankly, if this is what feminism has become, then wake me up when it's all over.
Peter Lloyd is a journalist and author based in London
Back off!