George Santayana

We must welcome the future, remembering that soon it will be the past; and we must respect the past, remembering that it was once all that was humanly possible.

Spanish Philosopher

Orson Welles

I can think of nothing that an audience won't understand. The only problem is to interest them; once they are interested, they understand anything in the world.

American Actor

Galileo Galilei

All truths are easy to understand once they are discovered; the point is to discover them.

Italian Scientist

Helen Keller

What we have once enjoyed we can never lose. All that we love deeply becomes a part of us.

American Author

Robert A. Heinlein

You can have peace. Or you can have freedom. Don't ever count on having both at once.

American Writer

Jimi Hendrix

It's funny how most people love the dead, once you're dead, you're made for life.

American Musician

Rainer Maria Rilke

One had to take some action against fear when once it laid hold of one.

German Poet

Dwight D. Eisenhower

The world moves, and ideas that were once good are not always good.

American President

Niccolo Machiavelli

The wise man does at once what the fool does finally.

Italian Writer

Henry David Thoreau

Use 'once' to stress the uniqueness of an event or experience.

Exclusive Event

'Once' often accompanies past simple to describe past events.

Past Tense

Imply that one action depends on another being completed first.

Conditional Action

List actions in the order they should happen, using 'once' to introduce.

Sequential Tasks

Points to a change from the past to the present.

Historical Context

Shows contrast between past and current situations.

Reflecting Change

Expresses something happens sometimes, but not often.

Occasional Frequency

Rare Event

Signals that one event immediately follows another.

Action Sequence

Indicates when the next step can occur after the first is done.

Task Completion

Sudden Unity

Two things happening at the exact same moment.

Dual Activity

 written by one of the smartest people in history? Let's give it a shot. The world's rarest fish has been stolen from the city aquarium. The police have followed the scent to a street with five identical looking houses. But they can't search all the houses at once, and if they pick the wrong one, the thief will know they're on his trail.

Can you solve...

 or perhaps the evolution of an intelligence capable of creating sophisticated technology is far rarer than we've assumed. After all, it's only happened once on Earth in four billion years. Maybe even that was incredibly lucky. Maybe we are the first such civilization in our galaxy.

Questions No One Knows...

 It seems like you're out of luck, unless you look at the rules carefully and notice an important exception. It's true that once you activate the switch in a contaminated room, it's destroyed and you can never go back. But there's one room that wasn't contaminated - the entrance.

Can you solve the virus...

 They descend from the canopy just once a week for a bathroom break. When sloths do move, it's not very fast. It would take a sloth about five minutes to cross an average neighborhood street. This unhurried approach to life means that sloths don't need very much muscle.

Why are sloths so slow?...

 It only does it about once a week but why does it come down to the ground to do it? And why does it nearly always choose to do so in exactly the same place? Whatever the reason, it must be very important, for a sloth on the ground is almost helpless.

The 'Busy' Life of the...

 each have corresponding areas of the brain where activity can be observed. But when researchers got the participants to listen to music, they saw fireworks. Multiple areas of their brains were lighting up at once, as they processed the sound,

How playing an...

 somebody asked me once what are you looking for in a relationship and I replied certainty I needed certainty in an uncertain world but we live in an uncertain world and so there has to be a

How to deal with...

 Katie said to me if something happens to me during the transplant I don't want you to be upset I was probably a lot more nervous than she was once we make a decision there's no going

Watch One Family's...

 we can turn this into a future driven by peace and prosperity and not once again repeat the tragedies of war. I thank you.

Are China and the US...

 once there they plunge into another world