I once read.. in the darkest hour.. even your shadow will leave you.. well... for me shadows is also a visible thing that the eyes can see.. yes.. of course you will think it has leave you if it is not visible to your eyes..
But.. does a thing really gone or not even there if it is not visible.. what if.. you can't see it.. but you can feel it.. that can we say it is not there.. or is it there?..