This preprint introduces mühân as an original conceptual proposal defining the first autonomous cardiac contraction during embryonic development as a biological threshold of life. The paper argues that commonly used criteria such as consciousness or neural activity represent later emergent phenomena and therefore cannot adequately mark the biological beginning of life. While the author affirms creation as originating from divine will (“Be, and it is”), the scope of this work remains strictly focused on identifying the earliest observable and self-sustaining biological rhythm. Mühân does not assign moral or legal status; it delineates a foundational biological continuity relevant to interdisciplinary discussions in biology, philosophy, bioethics, and Islamic thought. Declaration of originality: The term mühân and its conceptual framing are introduced here for the first time.