This week's Torah portion marks the first appearance of Nachson ben Amminadav.
Nachson is best known from the Midrash that appears in Tractate Sotah, 37a, saying that when the Israelites were at the Red Sea: "This tribe said: “I will not descend first into the sea,” and that tribe said: “I will not descend first into the sea.” Nahshon ben Aminadav (of the tribe of Judah) sprang forward and descended into the sea."
Nachson is a model "doer" in Jewish thought. He both has the faith in G-d that the Red Sea will part (and save him from drowning) and knows that he must take the personal initiative and walk himself, instead of waiting for G-d to carry him across.
Nachson is not just any Israelite. His is mentioned numerous times at the leader of the tribe of Judah, the largest tribe that eventually dominated the southern kingdom and lent its name to Judasim itself. Furthermore, Nachson's sister, Elisheva, is married to Aaron, the kohen gadol (high priest), and brother to Moses. Stepping back further, Nachson is a direct ancestor of Boaz, who through his marriage to Ruth becomes an ancestor to King David himself.
This Nachson then becomes a paradigm of how a vastly important leader over the newly free Israelite people (on the level of Moses, Aaron, Miriam, Joshua, Caleb, Elazar, and Pinchas) leads by example. Nachson exhibits the perfect mixture of faith in G-d and risk taking initiative.