How effectively does Donne combine thought and image in his poems?

Donne, like other metaphysical poets, uses images extensively but his imagery is invariably unusual and striking, often breath-taking but sometimes far-fetched and fantastic. The purpose of an image in his poetry is to define an emotional experience by an intellectual parallel.

Donne is a poet of wide range of knowledge and this helps him draw many striking images and comparisons. He is well versed in most of the subjects that excite the cultivated minds in his age. Astronomy, chemistry, geography, physiology, law, theology, voyages and discoveries are the fields of study in which he draws upon in differently for illustration.

It will be, however, admitted that Donne's imagery contributes a great deal to the difficulty which readers today experience in reading his poems, because it is a complex and curious process through which he brings together the opposites of life, body and soul, heaven and earth, the bed of the lovers and the universe, life and death, etc. in one breath. Huge concepts are closely packed together within a little space that they create a great confusion in the reader's minds. So, to understand him properly the readers must follow point by point the logical parallel to his emotions which his imagery provides.

"The Good Morrow" is pregnant with a number of images drawn from different sources: myth, the geographical world etc. To show the perfect world of love, Donne refers to the two hemispheres of the globe. The poet says that the world of the lovers has neither sharp north, nor declining west. They are unlikely to change or suffer a decline as their love is equal on both sides. Thus the imagery used in this poem, illustrates Donne's extravagant intellectual power for expressing a strong feeling.

Similarly, in "Twicknam Garden" the poet compares his passion of love to a poisonous spider and his feeling of jealousy to a serpent. With the help of conceits the poet draws the image of a spider, enmeshing everything and turning it to poisonous something, and the image of Eden where Eve was tempted to taste the forbidden fruit by Satan in the guise of a serpent:  

"But O, self traitor, I do bring The spider love, which transubstantiates all,And can convert manna to gall, And that this place may thoroughly be thought.True paradise, I have the serpent brought."

To sum up, Donne has effectively combined thought and image in his love poetry. By using wonderful and far-fetched similes, wits and conceits, logical arguments, he has brought out concentrated passion, intellectual agility and dramatic power which have given his poetry a kind of novelty and distinction from his predecessors. The nature of Donne's imagery calls for some of the strangeness felt by a modern reader who encounters his poetry for the first time.