The quote reflects Kafka's feelings of longing and the fleeting nature of time he experiences with Milena. He acknowledges that the day feels short and is primarily consumed by thoughts and moments he's sharing with her, suggesting a sense of urgency to express his feelings before time runs out. His choice of words indicates a deep emotional connection to her presence, which transcends the ordinary experience of a day.
Kafka contrasts the reality of the moment with the idealized, deeper connection he feels with Milena. He describes how her essence pervades his surroundings, filling even the most mundane aspects of the day with significance. This duality highlights the interaction between reality and emotion in his life, painting a vivid picture of his affection and the ephemeral quality of their time together.