"'if we observed the aviator carefully we should infer that he was unusually slow in his movements; and events in the conveyance moving with him would be similarly retarded- as though time had forgotten to go on. his cigar lasts twice as long as one of ours. i said 'infer' deliberately; we should see a still more extravagant slowing down on time; but that is easily explained, because the aviator is rapidly increasing his distance from us and the light-impressions take longer and longer to reach us. the more moderate retardation referred to remains after we have allowed for the time of transmission of light. but here again reciprocity comes in, because in the aviator's opinion it is we who are travelling at 161,000 miles a second past him; and when he has made all allowances, he finds that it is we who are sluggish. our cigar lasts twice as long as his.'

what a situation for envy! each man thinks that the other's cigar lasts twice as long as his own. it may, however, be some consolation to reflect that the other man's visits to the dentists also last twice as long."

--- from bertrand russell's "abc of relativity", who quotes eddington's "space, time and gravitation" and then added his own comments.