It is the mynd, that maketh good or ill, That maketh wretch or happie, rich or poore: For some, that hath abundance at his will, Hath not enough, but… - Edmund Spenser

Much like to the mole in Æsopes fable, that, being blynd her selfe, would in no wise be perswaded that any beast could see.

"O but," quoth she, "great griefe will not be tould,
And can more easily be thought, then said."
"Right so"; quoth he, "but he, that never would,
Could never: will to might gives greatest aid."
"But grief," quoth she, "does great grow displaid,
If then it find not helpe, and breedes despaire."
"Despaire breedes not," quoth he, "where faith is staid."
"No faith so fast," quoth she, "but flesh does paire."
"Flesh may empaire," quoth he, "but reason can repaire."

As when in Cymbrian plaine An heard of bulles, whom kindly rage doth sting, Doe for the milky mothers want complaine, And fill the fieldes with troublous bellowing.