Desires are strange! Arent they?

Had always observed desires to be weird:). They shoot up at one point of time and get suppressed at some other point of time. Desires drive spontaneous actions sometimes. Yet at few other times, its difficult to find out whether a desire is still alive or not! How to find out if a desire is still active? I guess the best way is to react what it asks for and leave it at that point of time. It will take care of itself from then. How do these desires behave like tides? At one point of time, one out of 1000 desires comes out and demands attention and at some other time it vanishes away! What was needed once upon a time is no longer needed. And what is needed now, for sure, will not be needed in the future!