In the beginning there were coins. Then there was paper money. Google, a company that has profited as if it were printing money, laments that with only a couple of variations (the charge card, the check), there have been few other ways since the dawn of commerce to pay for things.

And so today it launched Google Wallet, an app on an Android phone that stores virtual versions of your existing plastic cards. Walk into a store or restaurant, tap on a terminal with your smartphone, and you’ve paid your bill.

“Our goal is to make it possible for you to add all of your payment cards to Google Wallet, so you can say goodbye to even the biggest traditional wallets,” said Osama Bedier, Google’s Vice President of Payments. (Google got Jason Alexander of “Seinfeld” fame to play George in a promotional video.)

For the moment it will only link Citi MasterCards with Sprint Nexus S 4G phones. But Google said Visa, Discover and American Express are joining in too, and other wireless providers will doubtless follow. There’s also competition from Square, a firm headed by Twitter co-founder Jack Dorsey.

You can look on this as a convenience — no more scribbled signatures on charge-card receipts — or as one more way to separate you from your money. The charge card brought a sea change in 20th-century commerce — people spent dramatically more because they could no longer say, “Gee, I’m a little low on cash….” What happens if you don’t even have to pull out your wallet? You just tap with your phone — you probably had it out anyhow — and you’ve just spent $29.98.

There have been other, less comprehensive versions of wallet-less payment already; in many parts of the country, for instance, it’s rare to pay a bridge or highway toll without a plastic transponder on your windshield (E-Z Pass in the Northeast, I-Pass in Illinois, E-Pass in the South). ExxonMobil has experimented for years with Speedpass, a little chip you put on your keychain and wave at a gas pump to pay when you fill up.

The smartphone/wallet is potentially much bigger, if it catches on and becomes a common way of paying for things. It could be very, very convenient, though there may be the shock factor at the end of the month when you realize how much you’ve spent.