Answer:
I move without wings, Between silken string, I leave as you find, My substance behind.
I have an eye but cannot see, You'll head inside when you see me.
It cannot be seen, it weighs nothing, but when put into a barrel, it makes it lighter.
Once they sailed the sea, now they surf the web
I am the fountain from which no one can drink. For many I am considered a necessary link. Like gold to all I am sought for, but my continued death brings wealth for all to want more.
Brings the sky a lot closer.