From
陈子昂《
登幽州台歌》 (Chen Zi'ang, Tang, c. 696 CE), a 22-character masterpiece:
前不见古人,
后不见来者。
念天地之悠悠,
独怆然而涕下 (Ahead I see no ancients; behind, no one yet to come. I ponder heaven and earth in all their vastness — alone, mournful, tears falling). Widely considered the most concentrated expression of existential loneliness in classical Chinese poetry.