They are all arguing the same order of operations
Carnegie says action breeds confidence. Carlyle says accomplishment builds it. Van Gogh says paint and the voice goes quiet. Roosevelt says you gain it by facing things. Not one of them suggests you can arrive at confidence by thinking your way there, which is the method most people actually attempt. The consensus is unglamorous and worth taking seriously: confidence is a residue. It is what is left behind by having done something, and there is no known route to it that skips that step.
Ninety-three years, and six citations out of nineteen
Every datable line here falls between 1884 and 1977, and only six of the nineteen can be traced exactly. Both facts point the same way. Confidence as a subject for quotation is a twentieth-century invention — earlier writers wrote about courage, or about pride, or about knowing yourself, and treated confidence as a symptom rather than a goal. The modern form arrived with the self-help publishing industry, and it arrived without footnotes.
How do you build self-confidence?
Every writer in this room gives the same answer: by acting first. Carnegie puts it most directly — inaction breeds doubt, action breeds confidence — and Carlyle adds the mechanism, which is that accomplishment is what actually moves the balance.
Did Henry Ford say “whether you think you can or you think you can’t’?
It is universally credited to him and cannot be traced to his own writing or recorded speech, so it is labelled attributed here. The earliest known printings appear well after the phrase was already circulating.
Did Eleanor Roosevelt say “No one can make you feel inferior without your consent.”?
Usually sourced to This Is My Story (1937). It is not in that book. Archivists at the Roosevelt Library and the quotation researcher Ralph Keyes have both searched and found nothing — though Roosevelt did express the idea, at greater length, in 1935. It is filed here as attributed to Eleanor Roosevelt, which means widely credited and not traced to a primary source.