Q: I was born in 1942 and grew up with the expression “walking on eggs.” During the last 30 years or so, I hear only “walking on eggshells.” Has this expression morphed from “eggs” to “eggshells”?
A: In its first incarnation, the expression involved the whole egg, not just the shell. The original, 18th-century version was to “tread on eggs,” which the Oxford English Dictionary defines as “to walk warily, as on delicate ground.”
The only two citations for the whole-egg version in the OED are from the same author, Roger North, and appear in biographical works he published around 1734. Here are the quotations:
“This gave him occasion … to find if any slip had been made (for he all along trod upon eggs).” And, “He had his jury to deal with, and if he did not tread upon eggs, they would conclude sinistrously.”
The eggshell version showed up more than a century later, and has more examples cited.
The OED defines the phrase “walk on eggshells” and its variants as meaning “to be extremely cautious in one’s actions or words, esp. so as to avoid offending or angering others.”
The earliest citation given is from Wilkie Collins’s suspense novel The Woman in White (1860): “With that woman for my enemy … I walk, in your English phrase, upon egg-shells!”
In another citation, Ernest Rhys wrote in his Lyric Poetry (1913): “To speak of these things is to walk on egg-shells.”
The phrase also made an appearance in the title of a 1962 novel by Herbert Simmons, Man Walking on Eggshells.
And here’s a more recent example, from the British edition of Cosmopolitan magazine (1999): “He suffers from mood swings – you tread on eggshells because there’s no knowing what will set him off.”
All four OED citations for the expression since the early 1960s involve eggshells, not eggs. And Google hits run six-to-one in favor of eggshells.
In answer to your question, the expression does seem to have morphed. The eggshell version (whether one treads or walks on them) is by far the more popular form today.