terra incognita

It is needless to say how much interest attaches to the far larger unknown portion of this great island, the greatest terra incognita that still remains for the naturalist to explore, and the only region where altogether new and unimagined forms of life may perhaps be found.

1869, Alfred Russel Wallace, The Malay Archipelago, volume II, London: Macmillan and Co., page 428

The gap that remains in the interior will no doubt be eventually bridged over by railway communication; and thus the great continent will no longer be a terra incognita to the general world, who have hitherto only heard of the splendid country through which the railway will pass, from the reports of telegraph constructionists and overlanding parties.

1887, Harriet W. Daly, Digging, Squatting, and Pioneering Life in the Northern Territory of South Australia, page 242

Unfortunately, this great rocky tableland has of late years become almost a terra incognita to the nature-lover, as a result of the agreement which was made, after prolonged controversy, between the Peak District Society and the grouse-shooting landlords, inasmuch as, while permitting the traveller to skirt the shoulders of the hill, it excluded him wholly from its summit.

1922, Henry S. Salt, The Call of the Wildflower, London: George Allen & Unwin, →OCLC, page 109

The concept of the unconscious or an inner terra incognita, an unknown country of the psyche that precedes and predicates the Cartesian subject, the focal point of rational consciousness, was a revolutionary idea.

2009, Gary Clark, Quadrant, November 2009, No. 461 (Volume LIII, Number 11), Quadrant Magazine Limited, page 9