The writer expresses sorrow at being separated from the recipient due to illness and distance, reflecting on how their souls seem perfectly matched despite the separation. They critique modern atheism, preferring the philosophical depth of earlier thinkers like Spinoza and express a longing for intellectual and personal connections. The writer also comments on the inadequacies of contemporary French and English literature, praising classical and philosophical works instead, and laments the fleeting nature of existence, finding solace in the companionship of enlightened friends.