The one certainty is that death, sex and taxes always seem to come into the equation somewhere along the way.
I am not sure which of these is most important in the case of the Estee Lauder family, which this week formally launched a public offer of shares in the family cosmetics business. Estee Lauder herself, now in her late eighties, is no longer active in the management of the business she started back in 1946. Since 1982 it has been run by her son, Leonard.
The firm has sales of $2.9bn (pounds 1.8bn) a year and accounts for nearly 40 per cent of cosmetic sales in US department stores. There is probably nobody who does not now know that the actress Liz Hurley is the company's latest cover girl.
Cosmetics, like perfume and haute couture, is one of those business whose economics have the potential to defy gravity - if it works. The combination of low manufacturing costs, high advertising and promotional spend and snob appeal make it a wonderful opportunity to build a high- value brand. Profit margins of an established brand are huge. The power of the name is almost everything.
As it happens, stock markets around the world are hot on big-brand luxury products companies at the moment. Luxury brands took a bit of a battering in the early 1990s, with many of the biggest names surviving only on the back of heavy Japanese buying. The Japanese are the world's foremost purchasers of snob brands and one big question must be whether the revival will survive the current economic crisis in Japan.
But there is still enough momentum to allow Estee Lauder's bankers to put a stock market value of $3bn on the company.
As always, though, it pays to read the small print in these kind of offerings. Businesses that deal in products for the wealthy often seem to walk hand- in-hand with a taste for corporate extravagance. An exotic lifestyle seems to go with the territory.
And the market's fashion for cosmetics, it turns out, has come not a moment too soon for Ronald Lauder, Estee Lauder's second son.
He, so the Wall Street Journal informed us in a fascinating piece this week, is a man for whom the phrase spendthrift seems too kind. This is a man who finds it hard to live on $11m in salary and dividends that he took out of the company last year.
One reason for the share offering, so the paper reports, is to allow Mr Lauder to pay off his personal debts. These amount to $209m.
A good chunk of this has been spent on building an art collection and on various business ventures in Eastern Europe. Mr Lauder also spent $14m on an abortive attempt to get elected as mayor of New York.
Fortunately for shareholders, perhaps, the younger of Estee Lauder's two sons does not play an active management role in the company. But I suggest one should think twice, if only on principle, before investing in a business which managed to pay out a third of its profits last year - some $84m - to keep family members in a lifestyle that most of us can only envy.
Next, an update on the versatile mind of George Soros, the famous New York speculator turned philanthropist. A few weeks ago I suggested presumptuously that it was wise to take whatever he said about the stock markets with a large grain of salt.
Not because Mr Soros doesn't know what he is doing - you can hardly argue with the success he has had - but because his mind is essentially that of a trader, not an investor.
For traders, the key attributes are speed of thought and mental flexibility, the ability to change your mind in an instant and by 180 degrees if necessary. Long-term investors, by contrast, tend to ponder long and hard before deciding what to do. But once they have taken the plunge, it takes a lot more to shake the convictions at which they have so painstakingly arrived.
The style you adopt in dealing with your own money is largely a matter of temperament. It is only two months since the publication of Mr Soros' latest book. In it he was gloom personified about the outlook for the Tokyo stock market, about the prospects for emerging markets and about the possibility of a 'black hole' appearing in Russia.
He worried publicly about the possibility of a crash on Wall Street and the huge proportion of stocks now held over there by mutual funds. The proofs of the book went to the printers in the early part of this year.
Now, just a few weeks after his book appeared, he can be found singing from a very different song sheet. According to Barron's, the estimable Wall Street weekly, Mr Soros now reckons that Japan is on the up - which could have something to do, no doubt, with the fact that his Quantum Fund called the turn in both the Tokyo stock market and the yen at exactly the right moment when they bottomed out in the summer.
Russia is now on the mend and even the US market looks 'good and getting better'. In fact, Mr Soros says, the only worry he has at the moment is that "I have no worries".
The last time that happened was in the summer of 1987, only months before the October stock market crash of that year. The 1987 crash prompted one of the few big reverses in the otherwise irresistible rise of Mr Soros' investment empire.
My advice remains unchanged: don't believe a word of what he has to say this time either. If Wall Street's run is going to last well into next year, as now seems possible, it will be despite Soros's optimism, not because of it.