vid / vis

Seeing meant knowing

The Indo-European base behind this verb covered both sight and knowledge, and the two never fully separated. That is why evident means something you can see and therefore know, why provide means to see ahead and therefore prepare, and why the Latin phrase for "it is obvious" was simply videtur, "it is seen".

Greek kept the same link with a different word: oida, "I know", is formally a perfect tense of a verb meaning to see, so the Greek verb for knowing literally says "I have seen". The Sanskrit veda has the same shape and the same double sense, which is why the oldest Indian texts are called the Vedas — bodies of knowledge.

Two shapes, one rule

The infinitive gave English vid- words and the participle gave it vis- words, with very few exceptions. Visible, vision, visual, visualise, visa and television all use the participle. Video, evident, provide, revise, divide and individual use the infinitive form — though individual is worth a warning, since its second element is not videre but a related adjective.

The prefix behaves exactly as it does across the rest of the Latin vocabulary. Pro- plus videre is to see ahead; re- plus videre is to see again; super- plus videre is to see from above; tele- (Greek, "far") plus visus is to see at a distance — a hybrid coinage from 1900 that mixes a Greek prefix with a Latin root, which is normal in scientific naming.

• evident — e- + videre, "able to be seen out", hence obvious
• provide — pro- + videre, "see ahead", hence to prepare or supply
• revise — re- + videre, "see again", hence to look over and correct
• supervise — super- + videre, "look over from above"
• television — Greek tele + Latin visus, "seeing at a distance"
• video — the Latin word for "I see", chosen in 1950s broadcasting as the partner of audio

Where the root stops being obvious

Two very common words hide this root completely. Prudent is a worn-down form of providens, "foreseeing", and providence is the same idea given a theological name. Envy comes from invidere, "to look at with malice", from in- plus videre — the evil eye was literal in Latin.

A visit, meanwhile, is not a sight but a going to see: visitare was a frequentative of visere, itself a form of videre. English has kept the noun long after the verb narrowed to the point where visiting no longer implies looking at anything.