Can you understand the "To the Countess of Salisbury" Poem by John Donne 1614 ?

To the Countess of Salisbury
by John Donne 1614
Fair, great, and good, since seeing you, we see
What heaven can do, and what any earth can be:
Since now your beauty shines, now when the sun
Grown stale, is to so low a value run,
That his dishevelled beams and scattered fires
Serve but for ladies' periwigs and tires
In lovers' sonnets: you come to repair
God's book of creatures, teaching what is fair;
Since now, when all is withered, shrunk, and dried,
All virtue ebbed out to a dead low tide,
All the world's frame being crumbled into sand,
Where every man thinks by himself to stand,
Integrity, friendship, and confidence,
(Cements of greatness) being vapoured hence,
And narrow man being filled with little shares,
Court, city, church, are all shops of small-wares,
All having blown to sparks their noble fire,
And drawn their sound gold-ingot into wire,
All trying by a love of littleness
To make abridgements, and to draw to less
Even that nothing, which at first we were;
Since in these times, your greatness doth appear,
And that we learn by it, that man to get
Towards him, that's infinite, must first be great;
Since in an age so ill, as none is fit
So much as to accuse, much less mend it,
(For who can judge, or witness of those times
Where all alike are guilty of the crimes?)
Where he that would be good, is thought by all
A monster, or at best fantastical:
Since now you durst be good, and that I do
Discern, by daring to contemplate you,
That there may be degrees of fair, great, good,
Though your light, largeness, virtue understood:
If in this sacrifice of mine, be shown
Any small spark of these, call it your own.
And if things like these, have been said by me
Of others; call not that idolatry.
For had God made man first, and man had seen
The third day's fruits, and flowers, and various green,
He might have said the best that he could say
Of those fair creatures, which were made that day:
And when next day, he had admired the birth
Of sun, moon, stars, fairer than late-praised earth,
He might have said the best that he could say,
And not be chid for praising yesterday:
So though some things are not together true
As, that another is worthiest, and, that you:
Yet, to say so, doth not condemn a man,
If when he spoke them, they were both true then.
How fair a proof of this, in our soul grows!
We first have souls of growth, and sense, and those,
When our last soul, our soul immortal came,
Were swallowed into it, and have no name.
Nor doth he injure those souls, which doth cast
The power and praise of both them, on the last;
No more do I wrong any; I adore
The same things now, which I adored before,
The subject changed, and measure; the same thing
In a low constable, and in the King
I reverence; his power to work on me:
So did I humbly reverence each degree
Of fair, great, good, but more, now I am come
From having found their walks, to find their home.
And as I owe my first souls thanks, that they
For my last soul did fit and mould my clay,
So am I debtor unto them, whose worth,
Enabled me to profit, and take forth
This new great lesson, thus to study you;
Which none, not reading others, first, could do.
Nor lack I light to read this book, though I
In a dark cave, yea in a grave do lie;
For as your fellow angels, so you do
Illustrate them who come to study you.
The first whom we in histories do find
To have professed all arts, was one born blind:
He lacked those eyes beasts have as well as we,
Not those, by which angels are seen and see;
So, though I'am born without those eyes to live,
Which fortune, who hath none herself, doth give,
Which are, fit means to see bright courts and you,
Yet may I see you thus, as now I do;
I shall by that, all goodness have discerned,
And though I burn my library, be learned.
John Donne (/dʌn/ DUN; 1571 or 1572[a] - 31 March 1631) was an English poet, scholar, soldier and secretary born into a recusant family, who later became a cleric in the Church of England.[2] Under Royal Patronage, he was made Dean of St Paul's Cathedral in London (1621-1631).[1] He is considered the preeminent representative of the metaphysical poets. His poetical works are noted for their metaphorical and sensual style and include sonnets, love poems, religious poems, Latin translations, epigrams, elegies, songs and satires. He is also known for his sermons.
Donne's style is characterised by abrupt openings and various paradoxes, ironies and dislocations. These features, along with his frequent dramatic or everyday speech rhythms, his tense syntax and his tough eloquence, were both a reaction against the smoothness of conventional Elizabethan poetry and an adaptation into English of European baroque and mannerist techniques.[3] His early career was marked by poetry that bore immense knowledge of English society.... . Wikipedia