Interesting theory. The notion that some expressions of personality are obstructed by social 'noise' and thus benefit from solitude makes a lot of sense. By their reckoning, solitude is positive, voluntary and purposeful, the means to a desired end. In contrast, loneliness is negative, involuntary, a response to the loss of several sources of social support.<p>The OP (and others) suggest solitude's desiderata to be: 1) pursuit of a personal passion, and 2) disinterest in affirmation (or criticism) from others, 3) the belief that this journey will be preferable when taken alone.<p>Do the terms introvert and extrovert capture such personality quirks usefully? And are solitude and loneliness synonymous? I've long thought not.<p>As I understand the terms (informally), introverts are drained of energy when in a group while extroverts gain energy. But by that definition, loneliness should arise only when extroverts go it alone. Introverts should be immune. But not so, so there must be more to the story.<p>The best work I've read on the complexities of introversion and the merits of solitude is Susan Cain's marvelous book, "Quiet". As I recall, it confirms the OP's thesis.