There was so much expression in this 'ah!' that the course of my thoughts was changed at once, and I looked earnestly at Silvia. Could it have arisen from the difficulty she found in puzzling out alone those complex circles and triangles, which were quite beyond my comprehension? A cloud passed over her fair face, her lips seemed on the point of asking me a question, but she thought better of it, bent her head over her book and seemed once more absorbed in her abstruse study; but I noticed that her lips trembled. Poor child! She had never ventured to question me on that past, of which she must have learnt something from our old servants, and I, on my part, had never had the courage to revive the memory of my former sorrows by speaking of them to her — her curiosity, I knew, was most natural and lawful.