Robert A. Heinlein: Use

“Women and cats will do as they please, and men and dogs should relax and get used to the idea.”

Robert A. Heinlein Time Enough for Love

Time Enough for Love (1973)

For women , Women , Men , Dogs

“The mechanism is ages old. Tyrants used it centuries before the word "psychology" was ever invented. It works, too.”

Robert A. Heinlein book Revolt in 2100

Revolt in 2100 (1953)
Context: Take sex away from people. Make it forbidden, evil. Limit it to ritualistic breeding. Force it to back up into suppressed sadism. Then hand the people a scapegoat to hate. Let them kill a scapegoat occasionally for cathartic release. The mechanism is ages old. Tyrants used it centuries before the word "psychology" was ever invented. It works, too.

Age

“As for libertarian, I've been one all my life, a radical one. You might use the term "philosophical anarchist" or "autarchist" about me, but "libertarian" is easier to define and fits well enough.”

Robert A. Heinlein

1975 Statement to Judith Merrill, who had called herself a democrat and a libertarian, stating that such terms described him as well, as quoted in Robert A. Heinlein : In Dialogue with His Century, Volume 2: The Man Who Learned Better | 1948-1988 (2014), p. 389
Context: I think that describes me, too — still a democrat not because I love the Common Peepul and not because I think democracy is so successful (look around you) but, because in a lifetime of thinking about it and learning all that I could, I haven't found any other political organization that worked as well.
As for libertarian, I've been one all my life, a radical one. You might use the term "philosophical anarchist" or "autarchist" about me, but "libertarian" is easier to define and fits well enough.

Life

“My dear, I used to think I was serving humanity… and I pleasured in the thought. Then I discovered that humanity does not want to be served; on the contrary it resents any attempt to serve it. So now I do what pleases myself.”

Robert A. Heinlein book Stranger in a Strange Land

Source: Stranger in a Strange Land

Pleasure , Thinking

“Nothing uses up alcohol faster than political argument.”

Robert A. Heinlein book The Moon Is a Harsh Mistress

Source: The Moon is a Harsh Mistress

Alcohol

“When you vote, you are exercising political authority, you're using force. And force, my friends, is violence. The supreme authority from which all other authorities are derived.”

Robert A. Heinlein book Starship Troopers

Source: Starship Troopers

Exercises

“Death isn't funny. Then why are there so many jokes about death? Jill, with us — us humans — death is so sad that we must laugh at it.”

Robert A. Heinlein book Stranger in a Strange Land

Source: Stranger in a Strange Land

Death , Sadness

“What we think of as ‘Physical beauty’ is almost certainly a tag for a complex of useful survival characteristics. Smartness—intelligence—among them.”

Robert A. Heinlein book I Will Fear No Evil

Source: I Will Fear No Evil (1970), Chapter 2, p. 35

Beauty , Intelligence , Thinking

“This is the great day. This is the greatest event in all the history of the human race, up to this time. That is — today is New Year's Day of the Year One. If we don't change the calendar, historians will do so. The human race — this is our change, our puberty rite, bar mitzvah, confirmation, from the change of our infancy into adulthood for the human race. And we're going to go on out, not only to the Moon, to the stars; we're going to spread. I don't know that the United States is going to do it; I hope so. I have — I'm an American myself; I want it to be done by us. But in any case, the human race is going to do it, it's utterly inevitable: we're going to spread through the entire universe.”

Robert A. Heinlein

In a live interview with Walter Cronkite of CBS News, on the day of the first moonwalk (20 July 1969)
Robert A. Heinlein: In Dialogue With His Century, Volume I (1907–1949): Learning Curve (2010)

Hope , History , Star , Universe

“Mercifully, we stay our hand. Earth’s cities will not be bombed. The free citizens of Venus Republic have no wish to slaughter their cousins still on Terra. Our only purpose is to establish our own independence, to manage our own affairs, to throw off the crushing yoke of absentee ownership and taxation without representation which has bleed us poor.
In doing so, in so taking our stand as free men, we call on all oppressed and impoverished nations everywhere to follow our lead, accept our help. Look up into the sky! Swimming there above you is the very station from which I now address you. The fat and stupid rulers of the Federation have made of Circum-Terra an overseer’s whip. The threat of this military base in the sky has protected their empire from the just wrath of their victims for more then five score years.
We now crush it.
In a matter of minutes this scandal in the clean skies, this pistol pointed at the heads of men everywhere on your planet, will cease to exist. Step out of doors, watch the sky. Watch a new sun blaze briefly, and know that its light is the light of Liberty inviting all of Earth to free itself.
Subject peoples of Earth, we free men of the free Republic of Venus salute you with that sign!”

Robert A. Heinlein book Between Planets

Source: Between Planets (1951), Chapter 6, “The Sign in the Sky” (p. 74) - Speech given before the destruction of the nuclear-armed satellite Circum-Terra.

Men , People , Stupidity , Light

“The matter was still "Top Secret" and the subject of cabinet debates at the time of the Scranton Riot. Don't ask me why it was top secret, or even restricted; our government has gotten the habit of classifying anything as secret which the all-wise statesmen and bureaucrats decide we are not big enough boys and girls to know, a Mother-Knows-Best-Dear policy. I've read that there used to be a time when a taxpayer could demand the facts on anything and get them. I don't know; it sounds Utopian.”

Robert A. Heinlein book The Puppet Masters

Source: The Puppet Masters (1951), Chapter 24 (p. 127)

Secret , Girl , Boy , Time

“The death rate is the same for us as for anybody … one person, one death, sooner or later.”

Robert A. Heinlein book Tunnel in the Sky

Tunnel in the Sky (1955), Captain Helen Walker, Ch. 2

Death , Personality

“Ben, the ethics of sex is a thorny problem. Each of us is forced to grope for a solution he can live with — in the face of a preposterous, unworkable, and evil code of so-called "morals." Most of us know the code is wrong; almost everybody breaks it. But we pay Danegeld by feeling guilty and giving lip service. Willy-nilly, the code rides us, dead and stinking, an albatross around the neck.
You, too, Ben. You fancy yourself a free soul — and break that evil code. But faced with a problem in sexual ethics new to you, you tested it against that same Judeo-Christian code… so automatically your stomach did flip-flops… and you think that proves you're right and they're wrong. Faugh! I'd as lief use trial by ordeal.”

Robert A. Heinlein book Stranger in a Strange Land

"Jubal Harshaw"
Stranger in a Strange Land (1961; 1991)