Leiningen's motto in "Leiningen Versus the Ants" is spelled out as he contemplates the natural disasters he has successfully repelled on his plantation:
...Leiningen had met and defeated drought, Hood, plague and all other "acts of God" which had come against him-unlike his fellow-settlers in the district, who had made little or no resistance. This unbroken success he attributed solely to the observance of his lifelong motto: The human brain needs only to become fully aware of its powers to conquer even the elements.
(Stephenson, "Leiningen Versus the Ants," classicshorts.com)
This is a slightly more elaborate version of the classic axiom mind over matter, but without any paranormal intent. Leiningen believes his human intellect and individual abilities to be more powerful than nature's instinctive but unthinking events; Leiningen can act on reason and thought, instead of emotion or instinct, and therefore believes himself able to overcome anything nature can throw at him. Although the onrushing ants are collectively more powerful than Leiningen, he is able to use his reason to unleash an even more powerful natural force on them, and be victorious through thought and rational action.