The answer is: Salt

2 Ki 2:21

In 2 Kings 2:21, we see Elisha, the disciple and successor of Elijah, curing the water supply in Jericho using a rather unconventional method: throwing salt into the springs. This act might seem odd at first glance, but it’s a fascinating glimpse into the prophetic tradition and its symbolic meanings. Salt in the Bible frequently symbolizes purity, preservation, and even judgment, representing the idea of something being transformative or restorative – reflective of God’s character in bringing life amid adversity.

An interesting tidbit is how salt was used historically, not just in biblical times. It was prized like gold and traded extensively. In cities like Jericho - known for being an oasis despite surrounding desolation - fresh water sourced from springs was vital for survival. Elisha's act was not just about fixing water; it mirrored a greater, systemic restoration of life which foreshadowed the lush bounties that God preferred for His people, almost like an echo from Genesis, where the earth was teeming with abundant life.

Additionally, in Matthew 5:13, Jesus mentions believers being "the salt of the earth", further embedding salt's notion of flavoring life and imparting worth. In both these tales, salt serves as a link, emphasizing transformation and prosperity in the face of environmental and spiritual adversity. Hence, Elisha’s throwable "healing tool" turns out to be generations-rich with a message: integrity and goodness often stem from the simplest of acts.