When he smiles, his face is wistful and boyish, but once the energy of his forward motion is halted and he stops to ponder, his pale blue eyes seem to express sadness or loneliness. Doug Engelbart's voice, as he greets you, is low and soft, as though muted from having traveled a long distance, as though his words have been attenuated by layers of meditation. There is something diffident yet warm about the man, something gentle yet stubborn in his nature that wins respect.