Always, I insisted, for finite time intervals, however small, no perfect hedge was possible. [fact]

    Always, I insisted, for finite time intervals, however small, no perfect hedge was possible. [fact]
  

"What got Black, Scholes and Merton there," Samuelson recalled in 2000, "was their courage to take a final step that I was squeamish about: namely, I was loathe to accept the idealization of truly instantaneous rebalancings; always, I insisted, for finite time intervals, however small, no perfect hedge was possible."
Donald MacKenzie, An Engine, Not a Camera, loc. 612