But we know our selves least; Mere outward shews
        Our mindes so store,
    That our soules, no more than our eyes disclose
    But forme and colour.  Onely he who knowes
        Himselfe, knowes more.

Ode:  Of our Sense of Sinne.

One of the marked characteristics of Donne’s poetry is his continual comparison of mental and spiritual with, physical processes.  This sense of analogy prevailing throughout nature is with him very strong.  The mystery of continual flux and change particularly attracts him, as it did the Buddhists[28] and the early Greek thinkers, and Nettleship’s remarks about the nature of bread and unselfishness are akin to the following comparison:—­

                  Dost thou love
    Beauty? (And beauty worthy’st is to move)
    Poor cousened consener, that she, and that thou,
    Which did begin to love, are neither now;
    Next day repaires (but ill) last dayes decay. 
    Nor are, (although the river keepe the name)
    Yesterdaies waters, and to-daies the same.

Of the Progresse of the Soule.  The second
Anniversarie, 389-96.

Donne believes firmly in man’s potential greatness, and the power within his own soul: 

    Seeke wee then our selves in our selves; for as
    Men force the Sunne with much more force to passe. 
    By gathering his beames with a chrystall glasse;

    So wee, If wee into our selves will turne,
    Blowing our sparkes of virtue, may out-burne
    The straw, which doth about our hearts sojourne.

    Letter to Mr Roland Woodward.

And although, in the Progress of the Soul, he failed to give expression to it, yet his belief in progress is unquenchable.  He fully shares the mystic’s view that “man, to get towards Him that’s Infinite, must first be great” (Letter to the Countess of Salisbury).

In his treatment of love, Donne’s mystical attitude is most clearly seen.  He holds the Platonic conception, that love concerns the soul only, and is independent of the body, or bodily presence; and he is the poet, who, at his best, expresses this idea in the most dignified and refined way.  The reader feels not only that Donne believes it, but that he has in some measure experienced it; whereas with his imitators it degenerated into little more than a fashionable “conceit.”  The Undertaking expresses the discovery he has made of this higher and deeper kind of love; and in the Ecstasy he describes the union of the souls of two lovers in language which proves his familiarity with the description of ecstasy given by Plotinus (Enn. vi. 9, Sec. 11).  The great value of this spiritual love is that it is unaffected by time and space, a belief which is nowhere more exquisitely expressed than in the refrain of his little song, Soul’s Joy.[29]

    O give no way to griefe,
    But let beliefe
      Of mutuall love,
    This wonder to the vulgar prove
      Our Bodyes, not wee move.