If you think about it, the first form of intellectual property law was real estate law. From groundings in ground, elaborate intellectual constructs were created to describe interests in land which had no corporeal form, but were concepts or ideas. We are so used as lawyers to dealing with terms of years, easements, rights of way, life estates, leaseholds, profits a prendre, land patents and incorporeal hereditaments that we have virtually forgotten that these are all ideas only - the first intellectual property.
As we move into cyberspace, we find the same four (five if you count the publicity aspect of the right to privacy) forms of intellectual property law which apply to non-computerized intellectual property also apply in cyberspace: trade secret, copyright, patent and trademark.
