Why isn't literature considered sangha?

I never had any circle of friends, I love solitude more than anything - and honestly I want my life to stay that way, for the most part. I've always found my best friends in the quiet company of philosophy and literature. In my opinion this is no bad thing, but a true connection between people, it is a way of reaching out beyond the boundaries of time, a way to be moved spiritually. Why is this not "enough" in mainstream buddhism? I feel incomplete as I am simply not the kind of person to thrive in a communion. If I were to spend my spare time with other people I would simply be too exhausted from my very social job. The time I spend in solitude is necessary to maintain balance for me, but still everyone emphasize the importance of taking refuge in sangha, which makes me feel incomplete.