In order to hide the files again, there is an option in the Finder tab of Cocktail to "Show Invisible Items." Unchecking this should rehide the folder.
Mac OS X does a much better job of locking down the system and hiding the gorey details of the operating system files from the user than Windows. I've helped a number of Windows users who were trying to reclaim space and deleted those System files they never used. If you start deleting something you did not add to the system, you are risking the stability of the operating system, no matter what the OS may be.
And They Said the Mac Was Intuitive