Tlön is an imagined universe based on a mysterious encyclopedia. Borges relates his discovery of this encyclopedia in “Tlön, Uqbar, Orbis Tertius”. One of the main interesting aspect of this universe is that time is conceived as one, or perhaps non-existent according to one school stipulating that “present is undefined and indefinite, the future has no reality except as present hope, and the past has no reality except as present recollection.”.
Tlön people reject the possibility of space and matter too.
Overall, space and time are conceived as a series of mental processes.
The following is an amusing extract on defending the possibility of continuity and materiality against a conception of space and time as one, as a ‘monism’ :
“Of all the doctrines of Tlön, none has caused more uproar than materialism. Some thinkers have formulated this philosophy (generally with less clarity than zeal) as though putting forth a paradox. In order to make this inconceivable thesis more easily understood, an eleventh-century heresiarch conceived the sophism of the nine copper coins […].
On Tuesday, X is walking along a deserted road and loses nine copper coins. On Thursday, Y finds four coins in the road, their luster somewhat dimmed by Wednesday’s rain. On Friday, Z discovers three coins in the road. Friday morning X finds two coins on the veranda of his house.
From this story the heresiarch wished to deduce the reality—i.e., the continuity in time—of those nine recovered coins. “It is absurd,” he said “to imagine that four of the coins did not exist from Tuesday to Thursday, three from Tuesday to Friday afternoon, two from Tuesday to Friday morning. It is logical to think that they in fact did exist—albeit in some secret way that we are forbidden to understand—at every moment of those three periods of time.”
The language of Tlön resisted formulating this paradox; most people did not understand it.”
– Extract from Tlön, Uqbar, Orbis Tertius, in “Fiction” by J.L. Borges