1 Sinn Féin has won a historical victory and its supporters can justifiably celebrate for some days to come: By the count day, it was not a big surprise. But at the outset nobody saw this one coming. The party's election strategy was about managing decline.
Based on presidential, local and European election reverses, it pruned its electoral lists and lacked enough candidates to soak up the volume of votes available to it.
But it was a huge breakthrough moment for the party. Its leader, Mary Lou McDonald, and some key lieutenants, notably housing spokesman Eoin Ó Broin, campaigned very effectively.
They will know that electoral success can be fickle. In our recent history we have known the soaraway success of Labour twice - in the 1992 'Spring Tide' and 2011's 'Gilmore Gale'.
Labour's current embattled situation speaks for itself. The Sinn Féin leadership know this, since many of them have been involved for a long time.
2 The old '2.5-party system' has been delivered a huge blow: For many people of a certain age, Irish politics was all about Fianna Fáil dominating for long periods of time. The only change came sporadically when party number two, Fine Gael, combined with the half-party, Labour, to oust them.
Two general elections ago, in February 2011, party number two became party number one, and the half-party seemed to be getting far above its usual station.
At the time some hailed the turnaround as a "political revolution". Others more correctly dubbed it the swapping of Tweedledum for Tweedledee.
The more significant development has been the growth of 'ABFF/FG' (anyone but Fianna Fail/Fine Gael) over a generation.
Some 40 years ago, Fianna Fáil and Fine Gael got eight out of 10 votes cast. On Saturday, the combined Fine Gael-Fianna Fáil first-preference vote was closer to half that amount. Sinn Féin, which only opted to end its long-standing boycott of Dáil Éireann in 1986, has landed. Winning those seats was a hard slog and it took them up to 1997 to elect even one TD.
Other parties have also emerged - notably the Green Party - which has been a feature of Irish politics for 40 years.
3 Parties don't get credit for preventing or limiting calamity: Fine Gael found that appealing to voter gratitude for Brexit and a sound economy was a fool's errand.
Parties rarely get credit for calamities they prevent - conversely, voters more keenly remember the ones which happen on their watch.
Of the major parties fighting in General Election 2020 only one - Sinn Féin - had no share of government up to now. It had the biggest claim on the 'complaints department', especially when it came to deficiencies in health and housing.
In fact, details of the Ipsos MRBI exit poll for various media organisations was interesting on this. It showed that four out of 10 Sinn Féin voters made their choice because of issues around housing and homelessness. The party used the complaints department well.
Conversely, it is remarkable also that few of the other parties managed a fraction of the traction Sinn Féin got from the housing problems. Fianna Fáil was constrained by keeping the Fine Gael-led coalition in power and the remembering of its past economic misdeeds.
Messages from others, notably the embattled Labour Party, did not catch the voters' imagination. Mind you, it was hard to do that for Labour leader Brendan Howlin, who was a "cruel, but fair" public spending minister in times of recession.
4 Government-making will be easier said than done: There are 160 seats in the new Dáil, which will convene for the first time on February 20.
The magic majority number is 80-plus once the job of Ceann Comhairle goes to a member of a party which is less likely to figure in government. Even that action, taken as automatic for all the State's history, is not assured as the Ceann Comhairle is no longer given out by the incoming Taoiseach. Since 2016, the Ceann Comhairle has been elected by secret ballot of all TDs.
The potential permutations of getting to 80-plus seats and a government are all fraught with problems. For a start, you can forget the idea of a left-leaning alliance, led by Sinn Féin, and excluding both Fine Gael and Fianna Fáil - it does not have the numbers to get to the starting gate.
Involving Sinn Féin in coalition-making is a big challenge to the taboos of both Fine Gael and Fianna Fáil, and indeed for Sinn Féin itself. The Taoiseach has renewed his vows not to share government with Sinn Féin.
It is unclear whether a Sinn Féin-Fine Gael coalition would have the numbers - even assuming a device or devices could be found to get over the obstacles.
Numerically, a Fianna Fáil-Sinn Féin line-up might be more feasible. But the political difficulties are even harder here.
That brings us to another big political taboo - a grand coalition between Fine Gael and Fianna Fáil. Both are big organisations which have existed for decades and are in the business of staying in business. But it might come to that.
5 Do not be astonished if we have another election soon: This could happen because the parties cannot agree some kind of coalition in the coming weeks.
It could be because whatever arrangement that emerges lacks stability. In 1981 and 1982 we had three elections in 18 months before we got stable government. We do not need that kind of messing.
At all events, next time - be it early or late - Sinn Féin will have more candidates in the field.