I was myself a fair scholar. For years I pondered, so to speak, day and night over books, and filled my head with sound views - very sound ones, indeed - those of others. But I could no get to practical results. I then began to work and think independently. Gradually my views became unsound, but they conducted me to some sound results.

Nikola Tesla Quotes
November 14th, 1890Source:
The practical success of an idea, irrespective of its inherent merit, is dependent on the attitude of the contemporaries. If timely it is quickly adopted; if not, it is apt to fare like a sprout lured out of the ground by warm sunshine, only to be injured and retarded in its growth by the succeeding frost.
January 16th, 1910
But I hope that it will also be demonstrated soon that in my experiments in the West I was not merely beholding a vision, but had caught sight of a great and profound truth.
February 9th, 1901Source:
There is something within me that might be illusion as it is often case with young delighted people, but if I would be fortunate to achieve some of my ideals, it would be on the behalf of the whole of humanity. If those hopes would become fulfilled, the most exiting thought would be that it is a deed of a Serb.
The desire that guides me in all I do is the desire to harness the forces of nature to the service of mankind.
July, 1934
...the idea gradually took hold of me that the earth might be used in place of the wire, thus dispensing with artificial conductors altogether. The immensity of the globe seemed an unsurmountable obstacle but after a prolonged study of the subject I became satisfied that the undertaking was rational...
February, 1919Source:
If Edison had a needle to find in a haystack, he would proceed at once with the diligence of the bee to examine straw after straw until he found the object of his search... I was a sorry witness of such doings, knowing that a little theory and calculation would have saved him ninety per cent of his labor.
October 19th, 1931
Technical invention is akin to architecture and the experts must in time come to the same conclusions I have reached long ago. Sooner or later my power system will have to be adopted in its entirety and so far as I am concerned it is as good as done.
October 16th, 1927
The future will show whether my foresight is as accurate now as it has proved heretofore.
February, 1919Source:
The world, I think, will wait a long time for Nikola Tesla's equal in achievement and imagination.
February, 1943