How we cite our quotes:
A large corner of the handkerchief seemed to have been recklessly torn off to get rid of a mark; but she at once believed in the first image of 'the stranger' that presented itself to her mind. It was Deronda; he must have seen her go into the shop; he must have gone in immediately after, and repurchased the necklace. (2.6)
Isn't it kind of interesting how in this instance, Daniel tries to keep his identity a secret even though Gwendolen knows that he was the one who returned her necklace? Daniel always seems to maintain a secret identity (it's even secret to him – he doesn't know who his family is) even though everyone seems to think they know what his story is.
Having read Shakespeare as well as a great deal of history, he could have talked with the wisdom of a bookish child about men who were born out of wedlock and were held unfortunate in consequence, being under disadvantages which required them to be a sort of heroes if they were to work themselves up to an equal standing with their legally born brothers. But he had never brought such knowledge into any association with his own lot, which had been too easy for him ever to think about it—until this moment when there had darted into his mind with the magic of quick comparison, the possibility that there was the secret of his own birth, and that the man whom he called uncle was really his father. (16.10)
Here we get one of Daniel's key "a-ha!" moments. He's just starting to contemplate his background, which has always been a secret to him. Interestingly, he starts to think about who he is in comparison with the great works of literature that he has read.
[Daniel's] own face in the glass had during many years been associated for him with thoughts of some one whom he must be like—one about whose character and lot he continually wondered, and never dared to ask. (17.3.)
One of the ways that people understand their identity is through the ways in which they resemble the people they call their relatives. When Daniel looks at himself in the mirror, though, he doesn't think he resembles anyone else that he knows, leaving him to wonder whom in the world he does resemble, if anyone.