From the time he developed a capacity to reason, man has kept gaining understanding of the Ways of the World - his logical faculties sharpened by centuries of erring on the right side. His relentless enterprise has given him food and shelter and comfort and culture. His spirit for freedom, survival and dominion has resulted in discoveries that have sculpted civilization as we know it. But perhaps the greatest discovery came when he understood that he understood nothing.
Mr. Bhaskara Iyer (a Wizard at English whom I have had the good fortune of meeting) put it succintly, when he once talked about how he knew more about the language than me:
I am superior to you only in my ignorance. I know that I don't know, but you don't.
The laws of knowledge say that the light of knowledge extinguishes the darkness of ignorance. Thamaso Ma Jyothirgamaya. The light of knowledge also reveals the dusty corners of the barn you never knew existed. This is fundamental. This is even quintessential. The extent of ignorance is directly proportional to the extent of knowledge. The more you know, the more you don't know.
Enumerating what one does not know is a far more daunting task than listing out what one does. This is perhaps because though one knows that the former list is longer, one is somehow at a loss to generate it as easily as the latter. It is precisely this property of knowing the limits of one's knowledge that distinguishes the Wise from the Weak. Cognizance of the extent of one's ignorance is three fourths the knowledge itself.
To wit:90% of being smart is knowing what you are dumb at.
The quest for ignorance pushes one to probe deeper into the crux of the problem and to foray wider into the allied lands of the subject. Both contribute to the incessant process of learning and scholarship; and, ultimately, knowledge.
I have no hope of bettering R. L. Stevenson's words:
There is nothing more disenchanting to man than to be shown the springs and mechanism of any art. All our arts and occupations lie wholly on the surface; it is on the surface that we perceive their beauty, fitness, and significance; and to pry below is to be appalled by their emptiness and shocked by the coarseness of the strings and pulleys.
(in The Art of Writing)
The key to ignorance (and hence to knowledge) is to make this journey - the journey of a single step, if you will--the mental leap required to scrub off the coating from the surface, to contrive a mechanism to reveal the tricky apparatus underneath, to see in the assemblage an opportunity to learn, and to become aware of the strings and the pulleys in the first place.
This is the prime and only merit of ignorance. It is essential for knowledge. Indeed, a form of Knowledge that is free from Ignorance is not eternal Knowledge.
How can it be otherwise?