For Lent, this poster keeps the thoughts of Ash Wednesday front and centre and anticipates what Good Friday commemorates.
The italicized text at the top evokes the typography of prayer books, with a rubric and an Amen. This preface as a whole sets the stage as a gloss on the main body of the poster: hear, it says, the word of the Lord, and do according to its precepts. The passage, quoted from Ezekiel, is a precedent from the Old Testament for the practice of Ash Wednesday, which figures prominently in the middle of the poster in the form of a cross-shaped mark of ash.
Ars longa can be taken in two senses. In one sense, the art of living is so long and arduous in the face of corruption; in another, more perverse sense, the craft and subtlety of the human heart produces more abominations in one lifetime than we know what to do with. Either way, life is short; either way, the path of the Christian leads to the place where the Son of God, himself the eternal God, tempted as a human but blameless before God, was crucified.