In many of our talks I came across similar evidences of minute knowledge in various fields; nothing in the natural world was trivial to him or to be neglected. This great grasp was associated with a minute accuracy, and it was this double habit of mind which made Tennyson such a splendid observer, and _therefore_ such a poet, for the whole field of nature from which to cull the most appropriate epithets was always present in his mind. Hence those exquisite presentations of facts, in which true poetry differs from prose, and which in Tennyson's poetry appeal at once both to the brain and heart. But even this is not all that must be said on this point. Much of Tennyson's finest is so fine that it wants a knowledge on a level with his own to appreciate its truth and beauty; many of the most exquisite and profound touches I am convinced are missed by thousands of his readers on this account. The deep thought and knowledge are very frequently condensed into a simple adjective instead of being expanded into something of a longer breath to make them apparent enough to compel admiration. This it strikes me he consistently avoided. All the charm of all the Muses often flowering in a lonely word. Although many of the poems seem to me to be clothed with references to natural phenomena as with a garment, it can on the whole, I think, be gathered from them, as I gathered from our conversations, that the subject deepest in his thoughts was the origin of things in its widest sense, a _Systema Mundi_, which should explain the becoming of the visible universe and _define its different parts_ at different periods in its history. In this respect we have: Three poets in three ages born. Dante, Milton, and Tennyson, with their minds saturated with the same theme, and I can fancy nothing in the history of human thought more interesting or encouraging than the studies of this theme as presented to us in their works published we may say, speaking very roughly, three centuries apart. This of course is another story, but a brief reference to it is essential for my present purpose. All the old religions of the world were based upon Astronomy, that and Medicine being the only sciences in existence. Sun, Moon, and Stars were all worshipped as Gods, and thus it was that even down to Dante's time Astronomy and religion were inseparably intertwined in the prevalent Cosmogonies. The Cosmogony we find in Dante, the peg on which he hangs his _Divina Commedia_, with the seven heavens surrounding the earth and seven hells inside it, had come down certainly from Arab and possibly prior sources; the Empyrean, the _primum mobile_, the seven Purgatories, and the Earthly Paradise (the antipodes of Jerusalem) were later additions, the latter being added so soon as it was generally recognized that the earth was round, though the time of the navigator was not yet.