The decisions of leaders carry tremendous weight, often shaping the destiny of entire nations. While human beings are generally granted free will to navigate their lives, the absolute power held by a monarch operates under a different spiritual framework, subject to direct intervention from God. The heart of a king is compared to streams of water, such as aqueducts and canals [מצודת ציון, ביאור שטיינזלץ], or waters rushing down from mountains to form a powerful river [מלבי"ם]. Just as a person digs trenches to guide water toward useful areas and away from places where it might cause damaging floods [מצודת דוד, מלבי"ם], God actively guides and redirects the heart of a king.
The primary approach among commentators is that while a private individual possesses complete free will, a ruler is denied this absolute independence. Because a king's choices impact the entire public, granting him unchecked free will would pose a massive danger. A single flawed or cruel decision could unjustly destroy countless lives [רלב"ג, אלשיך, מלבי"ם]. Much like water, which has the power to either sustain multitudes or drown them, a king's decrees can bring either grace and peace or ruin and death. Therefore, to protect the greater good and ensure divine justice, God takes control of the king's will [אלשיך].
This divine guidance takes several forms. Sometimes, a ruler faces a complex dilemma, his thoughts divided and his mind unable to reach a conclusion. In these moments, God tips the scales and leads him to a final decision [אלשיך]. In other instances, God intervenes at the very beginning of the thought process, shifting the king's initial inclinations before a decision is even formed, much like diverting the flow of a spring at its source [מלבי"ם]. A clear demonstration of this control occurs when a leader issues a decree but suddenly changes his mind completely, often without realizing that a higher power directed his reversal [אלשיך, ביאור שטיינזלץ].
Although most view this dynamic as a unique limitation on government power, another approach argues that this principle applies to all humanity. The specific focus on a king serves as a logical deduction: if the heart of a mighty ruler is completely in God's hands, then the hearts of ordinary people certainly are as well. The practical message is that one should not place ultimate trust in flesh and blood leaders. They do not even control their own desires and decisions, as God alone directs their steps [עמנואל הרומי, אמרי דעת].