One metaphor for sati (mindfulness) is water. Like water, sati is transparent. It can take the shape of whatever it is aware of, and allow an intimacy, a deep knowing, of whatever awareness is shining its light on. Sometimes in the suttas, sati is described as limpid, meaning undarkened. The metaphor of seeing clearly runs through this practice. Limpid is used to describe eyes that are unclouded, eyes that are clear. When sati grows in strength, it’s effortless. It just effortlessly knows experience.