King Salman of Saudi Arabia, who came to the throne almost a year ago, is one of seven brothers by the same mother. As soon as he took power on the death of his half-brother Abdullah, he made sure that the next two men in line to the throne were from his section of the royal House of Saud - second in line was his own young son, Prince Mohammed bin Salman, and first in line was his late full brother's son, Prince Mohammed bin Nayef.
These three men confronted a region rocked by the upheavals of the Arab Spring in Syria, Yemen and Egypt, as well as a world economy that no longer looked to them as the chief source of its fossil fuels.
Shi'ites condemn Saudi execution of cleric
Shi'ites around the world condemn the execution of Shi'ite Muslim cleric Nimr al-Nimr by Saudi Arabia.
On top of all this, the Arab Spring had emboldened those in their kingdom who sought a greater voice in political affairs - chief among them the long-suppressed Shiite minority.
The execution of Nimr Baqir al-Nimr, a 56-year-old cleric and one of the leading voices of that minority, is more than simply a criminal punishment. It is a political signal from Saudi Arabia's royal triumvirate to the kingdom's internal and external rivals. And that signal can be summed up in the words of King Salman's late brother, Prince Nayef: "What we won by the sword, we will keep by the sword."
The first two places where this signal's reverberations will be felt are Iran and Bahrain. The Iranians are of course one of the dominant powers of the Middle East, wrestling with Saudi Arabia in Yemen and Syria and already with the upper hand in Lebanon and Iraq. They will now understand that where Saudi power prevails, dissident Shiites can expect no quarter.
That means that international talks aimed at ending the conflicts in Syria and Yemen have both become immeasurably more difficult from today.
Bahrain, a tiny island nation linked to Saudi Arabia's east coast by a causeway, is governed by a Sunni monarchy with close ties to the Saudis. But the majority of its population are Shiites. They too rose up during the Arab Spring of 2011, and Riyadh responded by sending in troops to enforce quiet while the Bahraini regime demolished the Pearl Roundabout which had been the focus of protests for greater political rights.
Bahraini Shiites will know that the sword now hangs over their heads too.
Inside Saudi Arabia, there will be young Shiites who - caught between the predictable oppression of the Saudi regime and the unpredictable threat of jihadist attacks by Islamic State and its ilk - will decide that the death of Nimr signals the end of attempts to change their circumstances by dialogue or protest. They too may look to the sword - and to Iran - to open a way out of their misery.
For Shiites around the world, Nimr is the latest in a long line of martyrs at the hands of tyrannical rulers. They will recall the proverbial utterance of their inspiration, the Prophet Muhammad's son-in-law Ali bin Abi Talib, that "the day of the oppressed over the oppressor is more severe than the day of the oppressor over the oppressed".
In Egypt, the Arab Spring brought democratic elections and the downfall of long-serving dictator Hosni Mubarak. The Saudis were amazed and appalled when their allies in Washington proved unwilling to back Mr Mubarak to the hilt. They were even more horrified when the Obama White House pursued dialogue and a deal with Iran over its nuclear program.
The Saudi response has been to freelance a new, far more aggressive policy across the region, leading a coalition to invade and bombard Yemen and bankrolling the return of military rule in Egypt, which is now effectively a wholly-owned subsidiary of Saudi Arabia.
The president who won Egypt's democratic elections - Mohamed Morsi - also waits in jail under a sentence of death, along with many other leaders of the now-outlawed Muslim Brotherhood. The execution of Nimr surely brings the clock closer to midnight for all of those men, with potentially dire consequences for Egyptian society.
The voices of all those in the Middle East who argue for a civic space that allows opposition voices and demands accountability from rulers have been weakened by this draconian act.
More worryingly, the voices of those who argue that the sword of the state only understands one language - that fire can only be fought with fire - have been strengthened, making bloodshed and violence more likely not only for Saudi Arabia and its interests around the world but for all those who are allies and business partners of the House of Saud. And that could mean many Western countries.
The poet John Donne said it best:
"Every man is a piece of the Continent, a part of the main; if a clod be washed away by the sea, Europe is the less, as well as if a promontory were, as well as if a manor of thy friends or of thine own were; any man's death diminishes me, because I am involved in Mankind; And therefore never send to know for whom the bell tolls; It tolls for thee."
Whether we like it or not, the bell that tolled for Nimr Baqir al-Nimr tolls loudly for all of us. We cannot afford to let it pass unheeded.
Maher Mughrabi is the Foreign Editor of The Age and The Sydney Morning Herald.