Keeping a diary in Irish was not a common practice but O'Sullivan (Amhlaoibh O Suilleabhain) showed remarkable originality and courage in keeping this record. He lived a full life as a successful businessman, a fearless worker in the cause of freedom and social justice, a lover of nature, an antiquarian, collector of manuscripts and enjoyer of good food and drink. O'Sullivan has left us with a remarkable contribution to the social history of Ireland as seen from the inside by a man of wide interests and deep understanding.