I couldn't think of much to say on the passing of the familiar, much-loved Mr. Nimoy so I'll leave it to another great SF personality who has already gone before:

*This is why I love SF. I love to read it; I love to write it. The SF writer sees not just possibilities, but wild possibilities. It's not just "What if..." but "My God, what if..." In frenzy and hysteria. The Martians are always coming. Mr. Spock is the only one calm. This is why Mr. Spock has become a cult god to us; he calms our normal hysteria. He balances the proclivity of SF people to imagine the impossible.

KIRK (frantically): Spock, the Enterprise is about to blow up!

SPOCK (calmly): Negative, Captain, it's merely a faulty fuse.

Spock is always right, even when he's wrong. It's the tone of voice, the supernatural reasonability; this is not a man like us; this is a god. God talks this way; every one of us senses it instinctively. That's why we have Leonard Nimoy narrating pseudo-science TV programs. Nimoy can make anything sound plausible. They could be in search of a lost button or the elephants' graveyard, and Nimoy would calm our doubts and fears. I would like him as a psychotherapist; I would rush in frantically, filled with my usual hysterical fears, and he would banish them.

PHIL (hysterically): Leonard, the sky is falling!

NIMOY (calmly): Negative, Phil; it's merely a faulty fuse.

And I'd feel okay and my blood pressure would drop and I could resume work on the novel I'm three years behind on vis-a-vis my deadline.*

As a bonus, an episode of the TV show "In Search Of" referenced above, narrated by Leonard Nimoy, about Phil's good friend Bishop James Pike:
https://www.youtube.com/watch?v=1AkrMe_5yOg