“For one who has not lived even a single lifetime, you are a wise man, Van Helsing.”
Dracula, to Van Helsing, who has discovered his secret
Dracula (1931)
As quoted in Wisdom for the Soul: Five Millennia of Prescriptions for Spiritual Healing (2006) edited by Larry Chang, p. 193
This is actually a pithy modern-day 'summary' of the "Abhaya Sutta" (AN 4.184). It appears in "Buddha’s Little Instruction Book" by Jack Kornfield (p88).
Unclassified
“For one who has not lived even a single lifetime, you are a wise man, Van Helsing.”
Dracula, to Van Helsing, who has discovered his secret
Dracula (1931)
“People who fear death live no longer than those who don't, and live scared.”
The Wizard Knight (2004), Volume 1: The Knight, Ch. 62
Fiction
Not by Twain, but from Edward Abbey's A Voice Crying In The Wilderness (1989).
Misattributed
Source: Silence Speaks, from the chalkboard of Baba Hari Dass (1977), p.39
Context: Q: What can I do to overcome my fear of death?
Odysseus, Book VIII, line 560
The Odyssey : A Modern Sequel (1938)
“Don't fear death, fear the un-lived life”
Variant: dont be afraid of death, be afraid of the unlived life.
Source: Tuck Everlasting