Firm as a stub or stump; stiff; unbending; unyielding; persistent; hence, unreasonably obstinate in will or opinion; not yielding to reason or persuasion; refractory; harsh; -- said of persons and things; as, stubborn wills; stubborn ore; a stubborn oak; as stubborn as a mule.
Many are stubborn in pursuit of the path they have chosen, few in pursuit of the goal. Friedrich Nietzsche
What is exciting is not for one person to be stronger than the other... but for two people to have met their match and yet they are equally as stubborn, as obstinate, as passionate, as crazy as the other. Barbra Streisand