Though usually adroit enough where her own interests were concerned, she made the mistake, not uncommon to persons in whom the social habits are instinctive, of supposing that the inability to acquire them quickly implies a general dulness.

Because a blue-bottle bangs irrationally against a window-pane, the drawing-room naturalist may forget that under less artificial conditions it is capable of measuring distances and drawing conclusions with all the accuracy needful to its welfare; and the fact that Mr.
Rosedale's drawing-room manner lacked perspective made Lily class him with Trenor and the other dull men she knew, and assume that a little flattery, and the occasional acceptance of his hospitality, would suffice to render him innocuous.

However, there could be no doubt of the expediency of showing herself in his box on the opening night of the opera; and after all, since Judy Trenor had promised to take him up that winter, it was as well to reap the advantage of being first in the field.
For a day or two after Rosedale's visit, Lily's thoughts were dogged by the consciousness of Trenor's shadowy claim, and she wished she had a clearer notion of the exact nature of the transaction which seemed to have put her in his power; but her mind shrank from any unusual application, and she was always helplessly puzzled by figures.

Moreover she had not seen Trenor since the day of the Van Osburgh wedding, and in his continued absence the trace of Rosedale's words was soon effaced by other impressions.
When the opening night of the opera came, her apprehensions had so completely vanished that the sight of Trenor's ruddy countenance in the back of Mr.Rosedale's box filled her with a sense of pleasant reassurance.

Lily had not quite reconciled herself to the necessity of appearing as Rosedale's guest on so conspicuous an occasion, and it was a relief to find herself supported by any one of her own set--for Mrs.
Fisher's social habits were too promiscuous for her presence to justify Miss Bart's.
To Lily, always inspirited by the prospect of showing her beauty in public, and conscious tonight of all the added enhancements of dress, the insistency of Trenor's gaze merged itself in the general stream of admiring looks of which she felt herself the centre.