Johnson's poem is about the meaningless nature of white collar work and its effect on the people who wear the "white, white collars."
One of Johnson's themes is the lack of individuality that characterizes his white collar workers:
. . . you know our clothes/Woke up this morning ans swallowed us like jewels/And ride up and down the elevators, filled with us. . . .
These unfortunates not only dress alike but also act alike--their clothes are identical, buildings "swallow" them, and they spend their time in elevators. At no point, do we get the impression that these people perform worthwhile, life-affirming tasks. They are anonymous in both in their appearance and their work.
The repetitiousness of this life is like the "the spray of light that goes/Around dance-halls among the dancing fools. . . ," and when the narrator says that his "office smells like a theory" he is making a new statement about white-collar work: this life generates no sensory impressions and, more important, it has no relevance to the physical world of being and action. His office smells like something that cannot possibly even have a smell because the space itself is not connected in any meaningful way to life's physicality. In other words, the office has no smell of life.
When we read the last four lines, which begin
. . . But in my belly's flames/Someone is dancing, calling me by many names/That are secret and filled with light and rise. . . ,
we understand that only in the narrator's imagination is there a life with sensations "filled with light," and he longs for a previous life in which he experiences those elements that made him feel truly alive. In his current circumstances, he lives in a space that is like a thought, a theory, totally detached from the world where his life was once "filled with light" and life.