Could this be the original poem pastiched by Dickens as Mrs Leo Hunter's 'Ode on an Expiring Frog' in Pickwick?
TO A FROG.
Poor being! wherefore dost thou fly?
Why seek to shun my gazing eye,
And palpitate with fear?
Indulge a passing trav'ler's sight,
And leap not on in vain affright;
No cruel foe is here.
I would but pause awhile, to view
Thy dappled coat of many a hue;
Thy rapid bound survey;
And see how well thy limbs can glide
Along the sedge-crown'd streamlet's tide,
Then journey on my way.
No savage sage am I, whose pow'r
Shall tear thee from thy rush-wove bow'r,
To feel th' unsparing knife;
No barb'rous schemes this hand shall try,
Nor, to prolong thy death, would I
Prolong thy little life.
Ah! let him not, whose wanton skill
Delights the mangled frog to kill,
The wreath of praise attain!
Philosophy abhors the heart
That prostitutes her sacred art,
To give one being pain. [Charles Snart, 'To a Frog', Elegant Extracts in Verse (2 vols, 1810) 2:141]
Newlan's Everyone in Dickens suggests the source may have been Horatio Smith's Gaieties and Gravities (1825) which contains the poem 'To a Log of Wood upon a Fire'. But I like this one better.
‘Could a rule be given from without, poetry would cease to be poetry, and sink into a mechanical art. It would be μóρφωσις, not ποίησις. The rules of the IMAGINATION are themselves the very powers of growth and production. The words to which they are reducible, present only the outlines and external appearance of the fruit. A deceptive counterfeit of the superficial form and colours may be elaborated; but the marble peach feels cold and heavy, and children only put it to their mouths.’ [Coleridge, Biographia ch. 18]
‘ποίησις’ (poiēsis) means ‘a making, a creation, a production’ and is used of poetry in Aristotle and Plato. ‘μóρφωσις’ (morphōsis) in essence means the same thing: ‘a shaping, a bringing into shape.’ But Coleridge has in mind the New Testament use of the word as ‘semblance’ or ‘outward appearance’, which the KJV translates as ‘form’: ‘An instructor of the foolish, a teacher of babes, which hast the form [μóρφωσις] of knowledge and of the truth in the law’ [Romans 2:20]; ‘Having a form [μóρφωσις] of godliness, but denying the power thereof: from such turn away’ [2 Timothy 3:5]. I trust that's clear.
There is much more on Coleridge at my other, Coleridgean blog.