In the course of a lengthy conversation in Hanoi, Harrison Salisbury of the New York Times was told by North Vietnamese Premier Pham Van Dong that the war in Vietnam is a "guerre sacrée" -- a "sacred war" embodying the spirit of national resistance that sustains North Vietnam's will to fight. The fact that Hanoi, confronted for over two years with the systematic devastation of resources that took a decade to amass and build, has stubbornly pursued its war aims argues strongly against summarily dismissing Dong's remark as mere propaganda. The willingness to sacrifice hard-won achievements for the sake of a larger, though uncertain, future goal -- here, the reunification of Vietnam -- has many precedents in wartime; like the constant calls Hanoi makes to its people . . .