Read it through once

“You may readily comprehend,” she added, “what my curiosity must be to know how a person unconnected with any of us, and, comparatively speaking, a stranger to our family, should have been amongst you at such a time. Pray write instantly, and let me understand it--unless it is, for very cogent reasons, to remain in the secrecy which Lydia seems to think necessary; and then I must endeavour to be satisfied with ignorance.”