Is Turning On an Incandescent Bulb on Shabbat a Torah Prohibition or a Rabbinic Prohibition?

This source-based Torah study examines the question: Is Turning On an Incandescent Bulb on Shabbat a Torah Prohibition or a Rabbinic Prohibition? It follows the canonical Hebrew discussion through the parasha and classical Jewish sources. This localized layer is a concise discovery summary rather than a full translation of the article body; practical or historical claims remain source-framed and subject to the canonical review status.