I should like to modify-perhaps rather to amend-what I have written about the 'immutability' of catch phrases by quoting from two letters, for I should hate to sound dogmatic on a subject that precludes dogma.
The earlier (1977) comes from Mr Robert Claiborne of New York City and Truro, Mass.:
While sharing your inability to define rigorously a catch phrase, I must cavil at your dictum 'they are immutable'. See (among many examples) be good…, before you came…, and better than a dig in the eye…. Indeed, the catch phrase, to the extent it is a form of folk wit, must, like folk songs, proverbs and the like vary both in time and in space. Thus their 'immutability' is relative. I would guess that the longer the life, and the greater the geographical distribution, of a c.p., the greater the variation. Granted, with the rise of broadcast communications, many c.pp. will be invented, spread and disappear without change-but others will, I think, still follow the traditional (and therefore variable) pattern.
This proposed modification has been urged both by several amicable reviewers and by knowledgeable, alert and intelligent friends, notably Prof. John W. Clark and Mr Vernon Noble. The latter wrote to me in 1978:
As an addition to your introductory note…, I would define a catch phrase thus: An observation or remark-often witty or philosophical, but not necessarily either-that has 'caught on' among a substantial number of people and has been repeated for a long period. It has tickled the imagination and has been accepted as a truism or as an apt commentary on current affairs, fashions or attitudes.
If one accepts this definition, it is often difficult to decide which quotation from the field of entertainment is justified for inclusion. There is no problem with radio and television, because knowledge of these media is widespread; but the theatre and the music-hall present difficulties, because the audience-taking the country as a whole-was [and is] restricted. In general, only those theatre and music-hall catch phrases which were snapped-up by the sophisticated (that is, those who were [and are] able to attend places of entertainment and spread [the phrases] in conversation), and those repeated in newspapers, [other] periodicals and in books, can be given the distinction: so many had a comparatively small circulation and a short life.
I really don't think [that, for instance] Robey's 'I meanter say' or Weldon's 'sno use' can be regarded as [eligible]; partly because of the [reasons mentioned]