The Same Train, Different Waters: Difference and Identity in Saussure and Deleuze

Introduction

The problem of identity, how something remains what it is while constantly changing, runs through both linguistics and philosophy. In the twentieth century, Ferdinand de Saussure and Gilles Deleuze each placed difference at the center of their thought, overturning the classical order in which identity comes first and difference follows. For Saussure, language is a system in which meanings exist only as relations of opposition; for Deleuze, being itself is a field of differentiation without fixed substance.

This essay brings these two projects into dialogue by examining Saussure’s example of the train and Deleuze’s analogy of the wave. Each illustrates how persistence depends not on material stability but on dynamic structure. By comparing these examples, we can see how Deleuze extends Saussure’s structural insight from the field of linguistics to the ontology of becoming.

Saussure: Difference and the Relational Nature of Identity

In the Course in General Linguistics, Saussure famously writes:

“In the language itself, there are only differences. Even more important than that is the fact that, although in general a difference presupposes positive terms between which the difference holds, in a language there are only differences, and no positive terms” (Saussure, 1916/1959, p. 120).

This reversal of traditional logic means that meaning does not precede the linguistic system; it emerges within it. Neither sounds nor ideas exist independently of their differential relations. A sign’s “value” depends not on any inherent content but on what distinguishes it from other signs.

To make this abstract principle tangible, Saussure offers non-linguistic analogies. One of the most striking is that of the train. We speak of “the 8:45 from Geneva to Paris” as the same train every day, even though the locomotive, carriages, and staff change constantly. Its identity persists because it occupies a specific position in a relational network — a timetable, a route, a sequence. The train’s “sameness” is not physical but structural; it depends on the relations that define it within the system of differences:

 “We assign identity, for instance, to two trains (‘the 8.45 from Geneva to Paris’), one of which leaves twenty-four hours after the other. We treat it as the ‘same’ train, even though probably the locomotive, the carriages, the staff etc: are not the same” (Saussure, 1916/1959, pp. 107–108).

Saussure thus replaces substance with relation, and identity with value. Language, like the train schedule, is a system of interdependent units that acquire meaning only through opposition. The mechanism of language, he observes, “turns entirely on identities and differences” (Saussure, 1916/1959, p. 107). Identity is therefore nothing but the stable pattern of differences maintained within a network.

Deleuze: Difference as Ontological Becoming

Half a century later, Gilles Deleuze radicalized this structural logic by applying it to being itself. In Difference and Repetition (1968), he argues that philosophy has long subordinated difference to identity. From Plato to Hegel, difference was treated as a deviation, negation, or limitation of the identical. Deleuze instead proposes to think “difference-in-itself” — a positive, productive principle that precedes identity and generates it through differentiation.

To illustrate this, Deleuze often refers to the wave. A wave appears continuous and self-identical, yet it exists only as a pattern of movement in a medium whose elements are constantly replaced. Each particle of water rises and falls in succession, never remaining the same, while the wave-form persists. Its identity is the identity of a process, not of a substance.

This dynamic mirrors Saussure’s train but operates at a deeper, ontological level. The wave exemplifies Deleuze’s idea of repetition, not the recurrence of the same, but the return of difference itself. “Repetition is difference without a concept,” he writes (Deleuze, 1968/1994, p. 28). What repeats is not an identical form but the differential relation that produces form. The persistence of the wave is the persistence of difference operating through time.

Deleuze’s ontology is thus a metaphysics of becoming. Every object or organism is a temporary stabilization of flows and intensities, an ongoing negotiation of internal differences. Like Saussure’s linguistic system, it is relational — but the relations are not between signs; they are between forces, intensities, and multiplicities. In both thinkers, identity is relational, but in Deleuze, the relations themselves are mobile, creative, and immanent to being.

Comparing the Train and the Wave

The train and the wave each dramatize a similar paradox: how the same can persist through difference. In Saussure’s linguistics, the train’s identity depends on its place within a system of differences that define values. In Deleuze’s philosophy, the wave’s identity depends on the continuous differentiation of its elements. Both reject the idea of identity as a fixed essence. Yet there is a decisive shift in scope.

Saussure’s system is structural and closed: the network of differences (the langue) forms a self-contained system. Deleuze’s ontology is processual and open: difference unfolds indefinitely in time, without totality or closure. We could say that Deleuze ontologizes Saussure’s insight. What Saussure discovered in language — that meaning is constituted by difference — Deleuze discovers in being itself.

Thus, the train stands for structural persistence, while the wave stands for dynamic persistence. Both are real, yet their reality lies not in substance but in relation and process. Identity, in each case, is an effect of difference maintained through time.

Conclusion

From Saussure’s structural linguistics to Deleuze’s differential ontology, the same principle reverberates: what endures is not what remains identical, but what continues to differ within limits of consistency. The train and the wave, each in their own register, show that identity is relational, not substantial — a function of pattern, position, and becoming.

Deleuze’s philosophy can be read as an expansion of Saussure’s copernican revolution: the discovery that meaning, like being, is born of difference. If Saussure revealed that “in language there are only differences,” Deleuze extended the insight to the world itself.

Everything, from thought to matter, is a train of differences crossing the moving waters of a river that never flows twice the same way.

References

Deleuze, G. (1994). Difference and repetition (P. Patton, Trans.). Columbia University Press. (Original work published 1968)

Saussure, F. de. (1959). Course in general linguistics (W. Baskin, Trans.). Philosophical Library. (Original work published 1916)