From Longman Dictionary of Contemporary Englishbe/lie at the bottom of somethingbe/lie at the bottom of somethingCAUSEto be the basic cause of a problem or situation Lack of money is at the bottom of many family problems. → bottom
Examples from the Corpus
be/lie at the bottom of something• Mind you're not found lying at the bottom of the steps with a broken neck like Amy Robsart.• His girlfriend had been woken by the noise, and had found him lying at the bottom of the stairs.• Holman lay at the bottom of the open grave where he'd been roughly dumped.• Knowing that self-interest lay at the bottom of his proposal did not prevent my being grateful.• The rest, including your own clothes, now lie at the bottom of some deep, evil-smelling swamp.• The female's sperm storage tubules are sausage-shaped and sperm lie at the bottom of the tube.• To deliver water from these depths the pumping machine has to be at the bottom of the well.• Your name will be at the bottom of the letter-why write it twice? 