Faced with a miraculous sight that defies the laws of nature, Moses pauses his journey to understand the vision before him. His reaction blends natural curiosity, intellectual observation, and profound spiritual humility in the presence of the first miraculous sign performed by a prophet [אבן עזרא]. Although he immediately recognizes the sight as divine, his humility prevents him from imagining that God would actually speak to him; he merely wishes to observe the wonder [ביאור יש״ר].
As Moses alters his course, commentators debate the physical and spiritual direction of his movement. The primary approach among commentators is that Moses seeks to leave his current path and step closer to the bush. Conversely, some suggest he is actually stepping backward. The light radiating from the bush may have been as blinding as the sun, preventing a close inspection, or perhaps gaining a proper perspective of such a grand sight on a mountain requires taking a step back [כלי יקר, פרדס יוסף]. Beyond physical movement, his change in direction represents an intellectual and spiritual shift. Recognizing the prophetic nature of the vision, Moses seeks to detach from his physical limitations, preparing to grasp the sight with a pure mind rather than relying solely on his physical senses [מלבי״ם]. This deliberate pause is a preparation for holiness. Understanding that profound and hidden matters must not be approached with arrogance or haste, Moses steps back in awe. Ultimately, this recognition of his own limits is precisely what draws him closer to the divine revelation [צרור המור, דברי דוד].
The core of Moses' astonishment lies in the nature of the fire itself. Observing that the bush is actively ablaze, his puzzlement over why it does not burn seems contradictory. Many explain that his wonder is focused on destruction, questioning why a bush engulfed in flames is not turning to ash [הכתב והקבלה, בכור שור, הדר זקנים]. Others read his reaction as a profound expression of shock, marveling at how a fire burning with such fierce intensity fails to consume the wood [רא״ש, חזקוני]. Initially, Moses suspects this might be a rare natural occurrence, perhaps a plant coated in a unique substance that fuels a fire without destroying its host. He attempts to draw near for a closer inspection, but God's subsequent warning not to approach clarifies that this is an absolute miracle rather than a trick of nature [תולדות יצחק].
Beyond the physical impossibility, the burning bush serves as a deep historical and spiritual metaphor. The fire symbolizes the enemy, harsh judgments, and the crushing weight of slavery, while the lowly bush represents the oppressed Israelites. Moses observes this and wonders how the Israelites can survive the fierce fire of exile without being destroyed. God's later mention of the Patriarchs reveals that it is their merit and divine providence that protect Israel from being consumed by the flames [אבן עזרא, העמק דבר, ברטנורא, צרור המור]. Alternatively, some interpret Moses' astonishment in the opposite direction, wondering why the fire of divine judgment is not yet destroying the Egyptians despite the heavy blows striking them [ספורנו].