His friendship with Ryder, in addition to the writings of Walt Whitman and American transcendentalists Henry David Thoreau and Ralph Waldo Emerson, inspired Hartley to view art as a spiritual quest.

Stieglitz also provided Hartley's introduction to European modernist painters, of whom Cézanne, Picasso, Kandinsky, and Matisse would prove the most influential upon him.

[2] Hartley traveled to Europe for the first time in April 1912, and he became acquainted with Gertrude Stein's circle of avant-garde writers and artists in Paris.

[9] In April 1913 Hartley relocated to Berlin, the capital of the German Empire where he continued to paint, and became friends with the painters Wassily Kandinsky and Franz Marc.

[10] Two of Hartley's Cézanne-inspired still life paintings and six charcoal drawings were selected to be included in the landmark 1913 Armory Show in New York.

[1] The drinkware calls back to the gatherings hosted by Gertrude Stein, where Hartley met Pablo Picasso, and Robert Delaunay.

After raising money through an auction of over 100 of his paintings and pastels at the Anderson Gallery, New York in 1921, Hartley returned to Europe again where he remained through the 1920s, with occasional visits back to America.

After a few months in Bermuda (1935), he traveled north by ship where he discovered a small fishing village in Blue Rocks, Nova Scotia and lived for two summers with the Francis Mason family of fishermen.

In September 1936 the two Mason brothers drowned in a hurricane—an event deeply affected Hartley and would later inspire an important series of portrait paintings and seascapes.

[8] His figure paintings of athletic, muscular males, often nude or garbed only in briefs or thongs, became more intimate,[8] such as Flaming American (Swim Champ), 1940 or Madawaska--Acadian Light-Heavy--Second Arrangement (both from 1940).

[8] In a personal memoir that was not finished, Hartley wrote "I began somehow to have curiosity about art at the time when sex consciousness is fully developed and as I did not incline to concrete escapades.

In addition to being considered one of the foremost American painters of the first half of the 20th century, Hartley also wrote poems, essays, and stories and published during his lifetime in many of the little magazines of the day, including one book of essays (Adventures in the Arts: Informal Chapters on Painters, Vaudeville and Poets.

Cleophas and His Own: A North Atlantic Tragedy is a story based on two periods he spent in 1935 and 1936 with the Mason family in the Lunenburg County, Nova Scotia, fishing community of East Point Island.

Hartley, then in his late 50s, found there both an innocent, unrestrained love and the sense of family he had been seeking since his unhappy childhood in Maine.

The impact of this experience lasted until his death in 1943 and helped widen the scope of his mature works, which included numerous portrayals of the Masons.

The independent filmmaker Michael Maglaras made a feature film, Cleophas and His Own, released in 2005, which uses a personal testament by Hartley as its screenplay.