From Art and Culture: http://www.artandculture.com/arts/artist?artistId=1060

The writer's childhood was marked by unusual circumstances that some believe led him to
become rather distrustful of the world around him. Against the backdrop of a country
undergoing economic turmoil, the writer-to-be found himself shuttled between a biological
and a foster family -- an especially horrifying situation given his cultureÕs emphasis on
familial roots.

While we cannot be certain how this unstable upbringing affected the developing artist, the
insecurities that run through his prose are unmistakable. Natsume's work echoes the
uncertainty and discontent now made familiar by the writing of European Modernists like
Freud, Woolf, and Hemingway. Despite its somewhat cute title, 1905's Wagahai wa
neko de aru (I Am a Cat) takes a decidedly sardonic view of Meiji-era Japan. The book
is written from the viewpoint of a cat living through the countryÕs transformation from a
feudal society to a modern one. Apparently, our feline protagonist prefers the traditional
over the inscrutable ways of the West -- the novel is chock-full of satirical commentary on
some of the more unsavory aspects of modernity.

Sarcasm transforms to a more sensitive melancholy in the later Kokoro (considered by
many to be his best work). The novel is a poetic rumination on the tragedy of the human
condition: Man is destined to be alone, and to know it. Relationships in the novel give rise
to passion and betrayal, a longing for connectedness and a lingering loneliness. Though
ÒKokoroÓ works on a personal level, it may still be read as NatsumeÕs continuing interest
in the crisis of his culture. For Natsume, alienation is the bane of the Japanese individual
torn between modernity and tradition.

Discontent and disillusionment continued as running themes throughout Natsume's work,
and he continued to develop motifs of isolation and suffering until the bitter end. Evidently,
the vitriol finally overcame him -- in 1916 he died of a chronic ulcer.

See also from http://www.city.kamakura.kanagawa.jp/english/bunjin/natsume_e.htm:

Natsume Soseki, novelist and scholar of English literature, was born in Tokyo in 1867. His real name was Kinnosuke. After graduating from Tokyo University, he taught English language and literature at the Matsuyama Middle School (in Ehime, Shikoku) and at the Fifth Higher School in Kumamoto, Kyushu.   In 1900, he was sent by the Education Ministry to study in London.

On returning to Japan in 1903, he began to teach English literature at the
First Higher School and Tokyo University. Also around this time, he was
invited by the poet and novelist Takahama Kyoshi to contribute stories to
the literary magazine Hototogisu. When "Wagahai wa Neko de aru" (tr I am a
Cat) and "Botchan" (Little Master; tr Botchan) were serialized in the
magazine, they established his reputation as an author.
This prompted Soseki to concentrate on writing. He gave up his teaching
positions in 1907 and joined the Asahi Shimbun newspaper. Soon he was
producing many notable stories, including the trilogy "Sanshiro" (tr
Sanshiro), "Sorekara" (tr And Then), and "Mon" (The Gate; tr Mon); and
"Higansugi made" (Until After the Equinox) and "Michikusa" (tr Grass on the
Wayside).

Besides fiction, Soseki also wrote cultural critiques, Chinese poetry and
haiku verse. From his days at Tokyo University, he was greatly influenced by
his fellow student, the poet and critic Masaoka Shiki, and produced a prolific
number of poems.

Soseki developed the symptoms of tuberculosis from around 1904 and,
despite earnest efforts to convalesce, never fully recovered. And with the
added stress of other worries, he began to suffer from depression. On the
suggestion of his friend Suga Torao, he practised Zen meditation at the
Kigen-in hall of Engakuji Temple in Kita Kamakura. He was there from the end
of December 1904 until January 7th. He described this experience in "Mon"
and "Yume Juya" (tr Ten Nights of Dreams). Soseki died in 1916 of a gastric
ulcer; he was 49.