The quote "We all know how to be a child" from Mitch Albom's "Tuesdays with Morrie" reflects the innate simplicity and purity of childhood. It suggests that as adults, we often lose touch with the carefree spirit, curiosity, and unfiltered joy that define being a child. This loss can lead to a more complex, sometimes burdensome adult life, straying from the essence of what it means to experience life with wonder and openness.