Blake’s view that "without contraries [there] is no progression" constitutes a paradox which informs key theme of English Romanticism such as the source of poetic inspiration, the power of the imagination.
You might want to compare Shakespearean sonnets to Petrarchan sonnets. Both are specific sonnet forms, but they are different in terms of rhyme scheme and the pattern is more flexible in Petrarchan sonnets, or at least people have used it that way.
Petrarchan Sonnet “London” by William Wordsworth
Milton! thou shouldst be living at this hour: A
England hath need of thee: she is a fen B
Of stagnant waters: altar, sword, and pen, B
Fireside, the heroic wealth of hall and bower, A
Shakespeare, on the other hand, wrote in iambic pentameter.
Shakespearean Sonnet, Sonnet 1
When in disgrace with Fortune and men's eyes, A
I all alone beweep my outcast state, B
And trouble deaf heaven with my bootless cries, A
And look upon myself and curse my fate, B
You can see how it will be slightly different depending on how the rhyme scheme affects the meaning. It is an interesting idea to compare different sonnet types favored by different poets, such as Whitman and Shakespeare, and look at the difference in their styles as a result.
Rollo May (an existential psychologist) said that one must have courage to create. One of the reasons courage is required is that many artists have threatened the status quo. That is to say that some artists have gone against some of society's traditional values and rules. The artist is in conflict with some aspect of society and therefore reproduces a contrary. May also claimed that creativity comes from such moments of contrariness or conflict. That is, creativity emerges when the artist (or inventor, or activist, etc.) is working against some limit or something that (i.e. a contrary) opposes him/her.
Karl Marx was another thinker/author who believed that social progress emerged from the dialectical conflict of social classes. A dialectic is a contrary in which a thesis works with/against an antithesis and a synthesis is produced.
In "Preface to Lyrical Ballads," Wordsworth talks about the balance of restraint and passion (which could be compared to the stability and energy of heaven and hell respectively).
More generally speaking, you can look for other authors who write about conflicting ideas, oppositions, or contraries. There are plenty to choose from, including other Romantic poets. In "The Rime of the Ancient Mariner," Coleridge uses the contrary of destruction and regeneration. The mariner's tale, his responsibility to teach this moral that everything in nature has value, is created at the destruction of the albatross.
Since then, at an uncertain hour,
That agony returns:
And till my ghastly tale is tole,
This heart within me burns.
One writer to look at may be William Wordsworth. With an aesthetic that dwelt heavily in memories of childhood yet also sought to elevate nature, Wordsworth's writing presents a potential inherent contradiction.
The life of the mind, so central to his work, seeks to render nature as a part of the mind. If nature is a real place, outside of the mind, as well as a source of inspiration, how can it also be re-understood as being part of the mind?
Is there a subtle implication here that the mind has become its own, only inspiration, without real contact with the nature it has subsumed?
A hint of this complexity can be found in the poem, "I Wandered Lonely as a Cloud":
Wordsworth is exemplifying his contention that the events and emotions of the first three stanzas must recur in an altered mode of existence, neither in nature nor in history but in memory, if they are to occasion a poem.