We are reminded of his last trip up the stairs, to look in on the body of Teresa. Allegorically, Teresa's death removed from the ideal of Liberty the promise of material benefit, thus killing it as an ideal that could move men. In this sense, Liberty can no longer "get up the stairs" to its old status as an idealistic crusade.

I see another meaning here, in which the novel has taken Linda further "up the stairs" than Giorgio. While Giorgio represented the Republic of Liberty, this section of the novel deals with no single political doctrine. Instead, Linda represents lawful society as such, contrasted with the utopian desire to transcend all politics. We have gone to a much higher level of abstraction.