This text explores the nature of traces left by past events, distinguishing between external and internal types. An external trace serves as evidence of a past occurrence, yet its creation and persistence rely on the cooperation between the trace-maker and the medium that receives it. The author emphasizes that for a trace to remain recognizable and interpretable over time, the medium must actively participate in its preservation. Using the metaphor of wet soil versus dry rock, the text illustrates how different environments facilitate or hinder the recording and retention of information. This necessity for interaction leads to the concept of internal memory, which can be established both intentionally and unintentionally. The effectiveness of internal memory is thus evaluated by its capacity to actively maintain these traces in a legible form. Ultimately, the document presents a philosophical reflection on memory as an active process of preservation and interaction, where the quality of the record depends on the synergy between the acting force and the receptive environment.