Irene is acknowledging a barrier between her and Clare, comparing it to a racial barrier by stating, "Between them, the barrier was just as high, just as broad, and just as firm as if in Clare did not run that strain of black blood." She insinuates a racial barrier, or a color line, here between them, but as with everything in this novel, this barrier is about much more than just race. Passing, and the complications that accompany it, complicate these barriers. But what Irene fails to realize is that while she is not passing racially, she too has secrets that alarm her and endanger her.