The first is nice weather - proper sweat-behind-the-knees sun, the kind that allows small children to run around George Square in bathing suits just for the sheer joy of it, ice lolly in hand, slathered in white lotion.
The second is a sense of true anticipation that something very special is upon us and that we are responsible for. Yes, we have our triumphs as a city, and there is no denying we have much to be proud of, but seldom have scenes of pure and utter holiday spirit been so rife in the heart of Glasgow: smiling men in resplendent African dress grabbing a passing Swedish couple and the four of them posing for a spontaneous pre-Games selfie.
A time for, yes, taps aff, but also the shoes and socks of a businessman asleep under a copy of the Financial Times in George Square, out for the count for a number of hours, work seemingly forgotten.
Yet, yesterday, these two rare things were a reality and these seemingly anecdotal stories true happenings. I saw it: me and the thousands of other people who were in the city centre. The way it spilled into the streets and rose both in terms of the warm, sticky air and the feeling of something close to hysteria, something I have never felt before.
Ebi Joseph, Rootchie Etonye and Ben Oye had travelled from Nigeria to be a part of it. They arrived two days ago, and are staying in Blythswood Square. Are they ready to try on this new coat of elation the city has found itself wearing?
"We just came over for the Games and are staying for the Opening Ceremony, then a little longer," said Joseph.
"We brought a couple of wrestlers, too," interrupted Etonye. "We brought a couple of wrestlers from Bayelsa State. We're going to get tickets for that, of course. We've brought all the merchandise with us, so we're ready to show people. We're ready to cheer, ready for the experience, ready to do this."
Toby Berry, from Brighton, had taken a slightly more relaxed approach to the planning of his trip to Glasgow, but echoed the same sentiments.
"I've just arrived today and I'm staying in Glasgow, though it's with someone I don't even know. All I know is it's... in a house somewhere. Kind of like a couch-surfing idea.
"I've got quite a few tickets - the opening ceremony, athletics, and hockey. I went to the Olympics in London and that was a pretty good experience, I thought it would be a similar thing here so up I came.
"I've been to Glasgow before - a couple of years ago and stayed for a few days. It's a lot warmer now than it was the first time I came. The Games will bring people into the city for the first time, and they'll stay to have a look around which is a good thing for Glasgow.
"It's hard to say what I'm most looking forward to - but the feeling of actually being inside each venue is going to be hard to beat. Experiencing the whole atmosphere of the city over the next week-and-a-bit, too."
Yesterday, the rest of the city had not yet caught up with the enthusiasm of the core, still in preparation for the days to come. From today, however, Glasgow Green will be fully open to the public offering much in the way of eating and entertainment. The Kitchen will make up the focus of the Green - a foodie village of stalls and (if yesterday's set-up is to be trusted) the odd pop-up caravan-turned-cafe contained within the leafy confines of the park waiting to feed the masses.
Dalmarnock was, too, quiet and peaceful during the day. But there were glimpses of what is to come: a lone Barbadian cyclist speeding up and down the Clyde Gateway connecting the station with the arenas and stadia, his body navigating the bike as flawlessly as if his limbs were pieces of machinery.
Even the Gateway itself is anxious, anticipant. It creates a sort of catwalk between where you have travelled from and the much-hyped destination, with the latter always in sight, straight ahead, as if to build excitement further. Whether that's deliberate or not, it works.
On its pavements, officials waiting and waiting, parties of school children spilling across those broad pavements waiting too, everyone milling about waiting.
The athletes' village was as empty and quiet ahead of the opening ceremony as a receding wave. Maybe from a little down-time before the frenzy, but most likely because all bodies involved were just hard at work inside elsewhere, tweaking and refining.
As we know, this tweaking and refining has been seven years in the making. Seven years of polishing Glasgow's best bits, and a whole lot more besides done to areas deemed in need of an overhaul.
Lord Provost Sadie Docherty, speaking in George Square yesterday, highlighted just how much the city has benefitted from that: "I think it'll be absolutely fantastic for the next 12 days. I think you can feel the excitement in the city from both Glaswegians and people all across the world.
"I've just come half-way through George Square and I've already met Australians, Canadians, people from Harris, people from Mallaig, Edinburgh, Dundee... and they're all in Glasgow enjoying the weather and enjoying the buzz.
"For me personally, the renovation work and regeneration of the east end of the city has been incredible. I worked in the east end many years ago, in the early eighties, and for me to go back and see the change has been fantastic.
"I'm hoping that the people from the east end of the city feel like they're benefitting from it, but the whole of the city will too, and if we continue to have this good weather my greatest wish will be that a great many people will want to come back here on holiday, business will bring conferences into the city and perhaps some industrial engineering type jobs as well."
Of the whole thing there will, undoubtedly, be naysayers. But this is our Glasgow and the way it looked yesterday, and the way it looks today and for the next 11 days is the way I always want to remember it. Vital, hopeful, and prosperous.
No one knows how it will feel to host the Games, or even how it will feel to be the focus of attention for myriad positive reasons: how could we?
But what an opportunity for the city to say both that it can stand alone and be great, and also be proud to host and be a part of something that celebrates teamwork and inclusivity.
All this, and no sport has even happened yet. What stories must yet be in store.