But those who do not welcome the future should consider this: in denying progress it is not the future that they condemn, but themselves. They are inoculating themselves with a fatal disease, the past. There is only one way of denying tomorrow, and that is to die.

[Mais que ceux qui ne veulent pas de l’avenir y réfléchissent. En disant non au progrès, ce n’est point l’avenir qu’ils condamnent, c’est eux—mêmes. Ils se donnent une maladie sombre; ils s’inoculent le passé. Il n’y a qu’une manière de refuser Demain, c’est de mourir.]

Victor Hugo (1802-1885) French writer

Les Misérables, Part 4 “St. Denis,” Book 7 “Argot,” ch. 4 (4.7.4) (1862) [tr. Denny (1976)]
    (Source)

(Source (French)). Alternate translations:

But let those who desire not the future, think of it. In saying no to progress, it is not the future which they condemn, but themselves They give themselves a melancholy disease; they inoculate themselves with the past. There is but one way of refusing To-morrow, that is to die.
[tr. Wilbour (1862)]

But those who desire no future ought to reflect; by saying no to progress they do not condemn the future, but themselves, and they give themselves a deadly disease by inoculating themselves with the past. There is only one way of refusing to-morrow, and that is by dying.
[tr. Wraxall (1862)]

But let those who do not desire a future reflect on this matter. When they say "no" to progress, it is not the future but themselves that they are condemning. They are giving themselves a sad malady; they are inoculating themselves with the past. There is but one way of rejecting To-morrow, and that is to die.
[tr. Hapgood (1887)]

But those who do not want the future should think it over. In saying no to progress, it is not the future that they condemn, but themselves. They are giving themselves a melancholy disease; they are inoculating themselves with the past. There is only one way of refusing tomorrow, and that is to die.
[tr. Wilbour/Fahnestock/MacAfee (1987)]