Hegel, the German philosopher, said that periods of happiness are empty pages in history. While peace and tranquility usually bring gains to financial markets, they tend to be slow-building and cyclical - depending on the state of the economy.
Much better, say the day traders and speculators, to have a little volatility - hit those peaks and troughs with the right trading strategies and make some speedy profits. All as part of a balanced portfolio, of course.
Nothing juices up market volatility quite like geopolitical tensions. But we have to be careful what we wish for as geopolitical flare-ups can inflict long-lasting damage on economies, financial markets and, not least, lives.
Putting countries at odds with each other has often resulted in devastating wars: we're not visiting this theme here, however, as wars can have surprising and impossible-to-predict outcomes on economies and markets.
Instead, we'll look at some of the more recent tensions - why they are important - and what impact they have on financial markets.
Let's define this as a "war of words". Never likely to develop into full-blown armed conflict, but aggressive enough in intent to keep market players nervously eyeing the next move of the antagonists.
Most recently, this example of geopolitical tension has been embodied by the relationship between the US and North Korea.
The chart above shows just how risk-sensitive assets react during times of sabre rattling. It shows the dollar-yen currency pair during the recent back-and-forth dialogue between the US and North Korea over the setting up of potential talks between the two countries.
Yen havens have been a popular destination for international funds during times of geopolitical stress, pushing the US dollar lower when tensions intensify and allowing the US currency to move higher as tensions ease.
Jane Foley at Rabobank explains: "In times of crisis, investors are more concerned about having access to their funds than the rate of return.
"It follows, therefore, that in periods of heightening risk appetite the opposite is true and investors are more likely to chase yield in less liquid markets."
The yen had been rallying strongly since the escalation of tensions that followed the latest missile test by the North on November 29.
Then, Pyongyang announced unexpectedly on the closing day of the Pyongchang Winter Olympics in mid-February it was interested in talks with the US - a moment of apparent détante that halted the yen's rally and pushed the dollar higher.
Several days later, the US administration responded with the demand that North Korean nuclear disarmament must be top of the agenda at any such meeting. The market reaction - a sharp rally for the yen that pushed the dollar lower - indicates the market must have expected a frosty response to US demands from Kim Jong-un's camp.
Another week on and the yen eases once more - driving the dollar higher - after a recent delegation of South Korean diplomats to the North report to Washington that Kim is willing to discuss disarmament and will refrain from further missile testing while potential talks are being arranged.
While much of the market volatility seen in February has been ascribed to fears of rising inflation and its likely impact on interest rates, it has also been underpinned by the increasing threat of policy backfire in the US following the enactment of tax reforms last year and trade tariffs on certain industrial materials, signed by President Trump this month.
"If they [US tariffs] are just the beginning of protectionism, economies could be hurt to a significant degree," says David Hauner at Bank of America Merrill Lynch.
Once other countries begin responding with retaliationary tariffs on US goods and materials, we have a trade war. No-one wins this war. Trump's intentions of boosting the ailing US steel industry could backfire horribly.
Tariffs will make foreign imports of cheaper steel into the US more expensive, putting a strain on manufacturers and, ultimately, introducing a greater likelihood of the kind of inflationary pressures that require deeper, confidence-sapping interest rate increases.
Hauner adds: "The real economic effect could be exacerbated by the impact on risk appetite, especially as the global cycle is universally considered as long in the tooth. Protectionism could become an excuse to unwind risk."
Look back at the dollar-yen chart above and note how the yen is back on the move higher - pushing the dollar lower - since the US tariffs were announced earlier this month.
Gold - another traditional haven asset - reacted in a similar way, climbing nearly 2.5% in the week following the announcement of the trade tariffs.
Sterling: Brexit and the UK vs Russia
The pound has seen some violent ups and downs since the UK's decision to leave the European Union following the June 2016 referendum.
Each new announcement prompts reaction from sterling, but none so violent as the initial sell-off that followed the referendum result. In the two days that followed the 23 June 2016 result, the pound lost more than 11%.
Bringing the Brexit reaction right up to date, however, the pound is currently rallying nearly 1% on Monday after it emerged talks with the EU were close to resolving the issue of a transition deal.
Tensions are now building between the UK and Russia following the poisoning by toxic nerve agent of a former Russian spy and his daughter in Salisbury earlier this month.
Tit-for-tat diplomatic expulsions followed the UK's insistence that Russian state involvement was the only plausible explanation - denied vehemently by Moscow.
Geopolitical tensions are an ever-present threat to risk appetite in the financial markets, and while Brexit and US/N Korea threats appear to be easing, the threat of trade wars and increasing US isolationism, as well as Russian intervention on the global stage, are perceived as growing threats.
Meanwhile, in the US President Trump has sacked Rex Tillerson as Secretary of State, replacing him with the hardline conservative Mike Pompeo, who wants to roll back on the department's deal with Iran.
Should geopolitical tensions increase in 2018, look for the havens if you want to ride it out. Yen, Swiss franc, gold. Indeed, safety is most likely to be found in high-grade bonds such as US Treasuries and Japanese Government Bonds - but if the inflationary outlook rises, gains here will be hard won.
If you want to benefit from the added volatility that's likely to accompany such increases in tensions, then be careful of your timing - don't push too hard for gains and miss the opportunity to exit at the right time.
The biggest areas of volatility are likely to come from emerging markets as investors sell down their exposure to risk, so look for big moves in currencies such as the Turkish lira, Russian rouble and South African rand.
Equity markets will react to any likely impact on economic growth, so look out for signs of rising inflation and the reaction of policymakers to rising price pressures.