That Robert Browning, the poet, possessed wide and multifarious learning is evident to a casual reader of his poems. The careful reader is impressed by the range and extent of his learning which includes much of what is called hole-in-the-corner knowledge, a familiarity with out-of-the-way topics and incidents that few readers possess. The scholarship of the past two decades has begun to give us a good deal of knowledge upon the nature of Browning's learning, and we are in a fair position now to estimate how much of the poet's knowledge was systematic and well-ordered, and how much of it was haphazard and based upon a following-up of this or that temporary interest. The letter which is the heart of this paper and which is published for the first time below will shed light upon this problem in an area in which Browning's training was probably most systematic.