Je was op zoek naar: indomitability (Engels - Spaans)

i believe in the indomitability of the human spirit.
creo en lo indomable del espíritu humano.

your indomitability and ability to survive all that the dark throws at you arises from this.
su habilidad indomable para sobrevivir a todo lo que la oscuridad les ha arrojado surge de esto.

recall these harrowing cases: barbès made an accusation against the heroic blanqui – and blanqui, in spite of his forty years of solitary confinement, in spite of his exemplary life and his indomitability, could never get rid of the infamous slander.
hay que recordar ciertos casos lamentables: barbés acuso al heroico blanqui y blanqui, a pesar de sus cuarenta años de reclusión, a pesar de toda su vida ejemplar, de su vida indomable, jamás pudo quitarse de encima la infame calumnia.