“Is it for this purpose that we are strong—that we may have light burdens to bear?”

Source: Argonautica, Book I, Lines 109–110

Source: Dracula

A Dynamical Theory of the Electromagnetic Field (1864), §20.
Context: The general equations are next applied to the case of a magnetic disturbance propagated through a non-conductive field, and it is shown that the only disturbances which can be so propagated are those which are transverse to the direction of propagation, and that the velocity of propagation is the velocity v, found from experiments such as those of Weber, which expresses the number of electrostatic units of electricity which are contained in one electromagnetic unit. This velocity is so nearly that of light, that it seems we have strong reason to conclude that light itself (including radiant heat, and other radiations if any) is an electromagnetic disturbance in the form of waves propagated through the electromagnetic field according to electromagnetic laws.

Interview for Women's E News, 21 Leaders for the 21st Century (2008)

The bold portions are one of seven quotes inscribed on the walls at the gravesite of John F. Kennedy at Arlington National Cemetery.
1961, Inaugural Address
Context: Now the trumpet summons us again — not as a call to bear arms, though arms we need; not as a call to battle, though embattled we are — but a call to bear the burden of a long twilight struggle, year in and year out, "rejoicing in hope, patient in tribulation" — a struggle against the common enemies of man: tyranny, poverty, disease, and war itself. Can we forge against these enemies a grand and global alliance, North and South, East and West, that can assure a more fruitful life for all mankind? Will you join in that historic effort?

Reported in Josiah Hotchkiss Gilbert, Dictionary of Burning Words of Brilliant Writers (1895), p. 88

Samuel Hartlib (1600–1662) cited in: Walter Harte. Essays on Husbandry (1764), p. 3.

Source: The Tales of Alvin Maker, The Crystal City (2003), Chapter 4 “La Tia” (p. 72).