It's rare for a European to be honored in the way that rock art expert George Chaloupka was recently by an aboriginal (土著). 'He fell in love with our country, our culture and especially our rock art,' said Mick Alderson, the Aboriginal chairman of Kakadu National Park's board of management. 'Perhaps, more importantly, he also fell in love with our people. This was based on respect for our people and their knowledge. In turn, George has our respect--more than any other European I know.' Alderson's praise was read out at a party to mark 65-year-old Chaloupka’s retirement from the Northern Territory Museum and Art Gallery. Chaloupka was the dedicated amateur who discovered thousands of previously unidentified rock art sites across Arnhem Land. From them, he formulated the definite time sequence of those paintings, lending evidence to a much earlier aboriginal occupation of Australia than previously imagined. He fought the over-exploitation of the mineral-rich region, resulting in the establishment of Kakadu National Park. His work recognized the art on the rock walls as the world's oldest existing record of human expression, created thousands of years before the first designs were painted on the torch-lit cave walls of Europe. George has the respect from the aboriginals because ______.