_Lord John._ A cynic is a man who, etc....
_Lord John._ A cynic is a man who, etc.... (_Lights cigarette_).
_Lord John (lighting cigarette)._ A cynic is a man who, etc.
Better, but leaves much too much to the actor.
_Lord John (taking out gold cigarette case from his left-hand upper waistcoat pocket)._ A cynic, my dear Arthur (_he opens case deliberately, puts cigarette in mouth, and extracts gold match-box from right-hand trouser_) is a man who (_strikes match_) knows the price of (_lights cigarette_)--everything, and (_standing with match in one hand and cigarette in the other_) the value of---- pff (_blows out match_) of (_inhales deeply from cigarette and blows out a cloud of smoke_)--nothing.
It makes a different thing of it altogether. Of course on the actual night the match may refuse to strike, and _Lord John_ may have to go on saying "a man who--a man who--a man who" until the ignition occurs, but even so it will still seem delightfully natural to the audience (as if he were making up the epigram as he went along); while as for blowing the match out he can hardly fail to do _that_ in one.
The cigarette, of course, will be smoked at other moments than epigrammatic ones, but on these other occasions you will not need to deal so fully with it in the stage directions. "_Duke (lighting cigarette)._ I trust, Perkins, that ..." is enough. You do not want to say, "_Duke (dropping ash on trousers)._ It seems to me, my love ..." or, "_Duke (removing stray piece of tobacco from tongue)._ What Ireland needs is ..."; still less "_Duke (throwing away end of cigarette)._ Show him in." For this must remain one of the mysteries of the stage--What happens to the stage cigarette when it has been puffed four times? The stage tea, of which a second cup is always refused; the stage cutlet, which is removed with the connivance of the guest after two mouthfuls; the stage cigarette, which nobody ever seems to want to smoke to the end--thinking of these as they make their appearances in the houses of the titled, one would say that the hospitality of the peerage was not a thing to make any great rush for....
But that would be to forget the butler and the three footmen. Even a Duke cannot have everything. And what his _chef_ may lack in skill his butler more than makes up for in impassivity.