这首英文诗的意思?诗是这样的:FRIENDSHIP May our friendship be not like the

这首英文诗的意思?
诗是这样的:
FRIENDSHIP
May our friendship be not like the tides,--
Tides rise,tides fall.
May it be like the ocean?
Whose face may show smile,frown,or anger,
But whose heart is at bottom unchanging.
May our friendship be not like the flower,--
Flowers bloom,and flowers fade.
May it be like grass and trees,
their leaves may wither,
but their roots live long.
May our friendship be not like the Moon,--
The moon waxes,it also wanes.
May it be like the stars?
They appear or do not appear in the sky,
but always exist with mysterious light.