Beginning in the trade in the 1950s, he specialised in ancient art and classical numismatics for over half a century.
Trading as Royal-Athena Galleries in New York, in 1990 he founded the magazine Minerva to focus attention on the international ancient art trade and archaeological discovery and in 1993 became one of the founding members of the IADAA, the International Association of Dealers in Ancient Art.
This association set up a Code of Honour that obliges each member to diligently question the provenance of every traded object.
Eisenberg had fought against illegal trafficking as early as in the 1950s and said that, after trading more than 40,000 objects, he had never bought a piece knowing that it was of dubious provenance.
