The quote from Milan Kundera's "The Unbearable Lightness of Being" suggests that individuals cannot truly understand their desires since they only experience one life. This singular perspective prevents them from comparing their existence to any previous or future lives, leaving them with a limited understanding of what they should pursue or value.

In essence, Kundera argues that the lack of a broader context makes it challenging for people to grasp the significance of their choices. Without the ability to reflect on multiple lives or experiences, individuals may struggle to navigate their desires and realize what would bring them true fulfillment.