The idiomatic phrase in and of itself means without other factors in consideration, but it is often used solely for emphatic purpose. Avoid the phrase in careful writing, since cleaner wording can replace it in likely all cases. Prefer The weather was not solely responsible for the poor attendance, which is clearer in intention and cleaner in prose, to The weather, in and of itself, was not responsible for the poor attendance; likewise, prefer Knowledge alone (or Knowledge itself) is worth pursuing to Knowledge in and of itself is worth pursuing. Although old-fashioned to some, the phrase is fairly modern, with popularity rising sharply since the late 1800s.