Time

 Most complex word,

When asked at different times

Known to all but understood by some.

In bad times, like a cat

Walking slowly, watching everything 

But reacting to nothing, 

Gifts some difficulties but makes us strong.

Like a fallen leaf, which detaches from the tree

New leaves may arrive and bring greenery but the one which falls

Never returns.

Like a ball which rolls and gets lost,

It may be precious for one

But when ones lost never returns.

Like a river, never thinking of obstacle 

Just flowing and following its path

For some, it brings happiness, for some troubles, 

But still never comes empty-handed