Jose Emilio Pacheco’s poetry is characterized by a constant reflection upon time. In this paper, I analyze how this concern –which is common to thinkers like Bergson, Bachelard, Barthes and Ricoeur— becomes words in his poems Iras y no volveras and La arena errante. Human being lives the illusion of retaining the instants, of making them transcend. In those poems, fugacity of existence and perpetual change experienced by the speaker, are opposed to the art and literature’s wish of permanence.