This is an unusual book in its construction. Its front cover is perforated with horizontal slots that are fitted with metal sliding guides that can be moved side to side to reveal either one of two layers of text. When the guides are pushed to the right, the black text reads: "Perfect Lines - shoot headlong through the moment - Written in chalk to trace the passing. - As safely as consequences - They become in time to belong. - This is the track, - The line, - The Way. - Just as they will, - So do the tracks pass, - Constantly arriving - On grounds of expectation - It will come to pass. - Pass Pass" When the metal guides are moved to the left, the red text of the interior page is revealed. This poem reads, "Great structures - With roof tanks and penthouses - Stand like fixtures. - A ceaseless procession - To break the barrier and the boredom. - The next steel frame sums up the state of things, - and this statement is true: - 50 storeys held to be vertical - Lit structures - with metallic sides and outstanding elevators - Shine like meaning: - Of versions erected - By a a timely plumb line." -- Source of annotation: Marvin or Ruth Sackner.