What do they mean when they say "Triumph and disaster as imposters"?

I do not know in what context, Rudyard Kipling said that. I understand that it could mean that mankind is carried away by such factors like victory and defeat to judge a man and an event. On the other hand, the quintessence of man, lies neither in triumph and disaster. A balanced mind is not swayed by the victory and defeat in life. If you are puffed up with victory and demoralised with defeat, that shows the immature mind. That is why perhaps Rudyard Kipling call them as impostors.