Quasi-symmetrical maxims

"Enjoy what you do, and do what you enjoy."

"Mean what you say, and say what you mean."

These are maxims with an appearance of symmetry.  Logically they have a form similar to "If P then Q, and if Q then P" (though in the imperative rather than the indicative mood).  "If P then Q, and if Q then P" is equivalent to "P if and only if Q" or "P and Q are equivalent" - clearly symmetrical since the meaning (as represented by truth conditions) is left unaltered by interchanging "P" and "Q".

In reality, however, in natural language as distinct from pure logic, there is a subtle asymmetry in each maxim, due to the order in which its two parts are presented.

Before analysing this subtle asymmetry, I'll clear out of the way the related, much bigger and less subtle asymmetry between the two parts of the same maxim.  As the Hatter pointed out to Alice at the tea party in Alice's Adventures in Wonderland, "I mean what I say" is not the same thing as "I say what I mean" - and likewise the instruction "mean what you say" is not equivalent to "say what you mean", nor is "enjoy what you do" equivalent to "do what you enjoy".  The individual clauses of either maxim represent the instructions "If 'P' is true then make 'Q' true" and "If 'Q' is true then make 'P' true" - and these are not the same.  The examples given by the Hatter's other guests may help to make this clear: "I like what I get" is not the same thing as "I get what I like", and "I breathe when I sleep" is not the same thing as "I sleep when I breathe" [though for a character like the Dormouse the latter as well as the former might well turn out to be true!].

So to the more subtle asymmetry due to the order of the clauses, which is a matter of pragmatics (i.e. the way in which people use language in real-world contexts) rather than elementary logic.  To take the illustrative example cited in the Wikipedia article on Gricean implicature, the sentence "Mary had a baby and got married" is logically equivalent to "Mary got married and had a baby", but the two sentences invite different inferences from the hearer as to the order of events.  For the maxims cited above, there is not such a clear temporal ordering as in the marriage-and-baby example, but the order of the clauses may still be significant.  Doing and saying are outward actions, observable by other people, whereas enjoying and meaning are inner attitudes to what is done and said.  Hence the most obvious way to enjoy what you do, or to mean what you say, is to adjust your attitudes to your actions, whereas the most obvious way to do what you enjoy, or to say what you mean, is to adjust your actions to your attitudes.  So by putting "enjoy what you do" before "do what you enjoy" in the sentence, or putting "mean what you say" before "say what you mean", you are giving priority to the adjustment of attitudes to actions, and relegating the adjustment of actions to attitudes to second place.  The exact difference in implicatures between the two possible orderings will depend on the context (which may be such as to hint that second thoughts are best!), but, in many contexts, there will be a difference.

[I should add some more here, since the cases of "mean what you say" and "enjoy what you do" are not entirely similar.  Watch this space!]

Related topics

What is the difference?
Quasi-antonymous synonyms
Precision
Language use
Communication
Philosophy
Enjoying what you do
Directness
Priority