A japa mala carries 108 beads plus one larger bead, the meru, which is not counted and marks the point at which you turn back rather than crossing it. The number recurs throughout the tradition: 108 Upanishads in the standard list, 108 names in many stotras, 108 steps at certain temples. Explanations are plentiful. The distance from the earth to the sun is roughly 108 solar diameters, and to the moon roughly 108 lunar diameters. There are 27 nakshatras across four quarters. Twelve zodiacal signs across nine planets.
The honest position is that no single derivation is decisive and the tradition has never insisted on one. What the number reliably does is impose a fixed count large enough that the mind cannot maintain interest in counting. That appears to be the functional point. A short repetition can be performed attentively by effort; 108 outlasts the effort, and somewhere in the middle the recitation continues without being driven, which is the condition the practice is aiming at.
This is also why the meru bead is not crossed. On reaching it you reverse direction rather than continuing around, so the practice has a shape with a beginning and an end rather than dissolving into an indefinite loop, and the count stays honest. Repetition here is not persuasion aimed at a deity who needs convincing; the mantra is treated as having its own potency, which is the position developed at length in Mantra Vidya, where sound is a means rather than a message.
The number matters less than what a long enough count does to the person counting. To see how sacred sound is understood as a science, explore more of The Living Sanatan Timeline.
Part 90 of 100 — Series II: To the Eternal
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