The answer is: Belshazzar

Daniel 5:6 - Belshazzar’s knees knocked together as he was overcome with terror, a physical manifestation of the intense fear he experienced in response to the writing on the wall.

In the dramatic tale of Belshazzar in Daniel 5, his knees knocking together is more than just a vivid image—it’s a symbol of deep terror! As the king feasted in arrogance, surrounded by lavish riches, he forgets the powerful lessons of his predecessor, Nebuchadnezzar, who learned humility the hard way. The suddenly somber scene shifts when the mysterious writing appears, unraveling his bravado like a cheap tapestry, leaving him quaking in fear.

Interestingly, the phenomenon of fear manifesting physically is not just a biblical event; it resonates with many cultures and the human condition itself. History has evolutionarily adapted to show that our body literally reacts to our fears—that fight-or-flight response can create muscle tension or shaking. Fear can turn a clever strategist into a quivering wreck, just as it did Belshazzar.

Moreover, this incident serves as a potent reminder of the powerful symbolism in biblical narratives. The "writing on the wall” indicates inevitable judgment and is still a psychological marker today heralding warned consequences. The walls of our lives too can become mirrors reflecting our choices.

So next time you’re faced with fear, remember that the courageous can also shake in their boots. Just like Belshazzar, it invites reflective moments where painful awareness fosters growth. The commandarial echo throughout ancient Israel's stories drives home that divine messages can come laden with urgency, indeed shaping destinies centered on actions taken or, in this case, not taken.