Definition of "unascertained"

Throughout all future time, as now, the human mind may occupy itself, not only with ascertained phenomena and their relations, but also with that unascertained something which phenomena and their relations imply.

1862, Herbert Spencer, “Religion and Science”, in First Principles, London: Williams and Norgate, page 17

A conjecture vaguely taking shape in his mind resolved itself to nothing again, and left him with only the ache of something unascertained.

1881, William Dean Howells, chapter IV, in A Fearful Responsibility, Boston: James R. Osgood and Company, page 38

This will dispose of the power of the five perhaps estimable but unknown individuals known as “independents” to control in accordance with their unascertained prejudices the self-defending labors of a great nation in the presence of an efficient foe.

1917 March 23, “When the House Meets”, in The New York Times, page 8