Which portion of this passage indicates that the narrator observed roderick usher trying to appear cheerful and friendly, in contrast to his "terribly altered" appearance?

upon my entrance, usher rose from a sofa on which he had been lying at full length, and greeted me with a vivacious warmth which had much in it, i at first thought, of an overdone cordiality—of the constrained effort of the ennuyé1 man of the world. a glance, however, at his countenance convinced me of his perfect sincerity. we sat down; and for some moments, while he spoke not, i gazed upon him with a feeling half of pity, half of awe. surely, man had never before so terribly altered, in so brief a period, as had roderick usher! it was with difficulty that i could bring myself to admit the identity of the wan being before me with the companion of my early boyhood. yet the character of his face had been at all times remarkable. a cadaverousness of complexion; an eye large, liquid, and luminous beyond comparison; lips somewhat thin and very pallid, but of a surpassingly beautiful curve; a nose of a delicate hebrew model, but with a breadth of nostril unusual in similar formations; a finely moulded chin, speaking, in its want of prominence, of a want of moral energy; hair of a more than web-like softness and tenuity; —these features, with an inordinate expansion above the regions of the temple, made up altogether a countenance not easily to be forgotten. and now in the mere exaggeration of the prevailing character of these features, and of the expression they were wont to convey, lay so much of change that i doubted to whom i spoke. the now ghastly pallor of the skin, and the now miraculous lustre of the eye, above all things startled and even awed me. the silken hair, too, had been suffered to grow all unheeded, and as, in its wild gossamer texture, it floated rather than fell about the face, i could not, even with effort, connect its arabesque expression with any idea of simple humanity.

in the manner of my friend i was at once struck with an incoherence—an inconsistency; and i soon found this to arise from a series of feeble and futile struggles to overcome an habitual trepidancy—an excessive nervous agitation. for something of this nature i had indeed been prepared, no less by his letter, than by reminiscences of certain boyish traits, and by conclusions deduced from his peculiar physical conformation and temperament. his action was alternately vivacious and sullen. his voice varied rapidly from a tremulous indecision to that species of energetic concision—that abrupt, weighty, unhurried, and hollow-sounding enunciation—that leaden, self-balanced and perfectly modulated guttural utterance.