The explorers were now (in the last days of July, 1805) at the head of the principal sources of the great Missouri River, in the fastnesses of the Rocky Mountains, at the base of the narrow divide that separates Idaho from Montana in its southern corner.

Just across this divide are the springs that feed streams falling into the majestic Columbia and then to the Pacific Ocean.

As has been already set forth, they named the Three Forks for President Jefferson and members of his cabinet.

These names still survive, although Jefferson River is the true Missouri and not a fork of that stream.

Upon the forks of the Jefferson Lewis bestowed the titles of Philosophy, Wisdom, and Philanthropy, each of these gifts and graces being, in his opinion, "an attribute of that illustrious personage, Thomas Jefferson," then President of the United States.