WASHINGTON – There is a fearful symmetry to oil prices.

When they were so high last summer, they were like the poet William Blake's fierce tiger, ripping into household income, ruining truckers and feeding inflation. But high prices spurred greater use of public transit, investments in alternate fuels and conservation – civic goods that could wear the guise of Blake's lamb.

Low prices are a lamb for budgets and inflation. Lurking in the background, however, is the tiger. From Texas to Canada to the Middle East, investments in expanding oil supplies are faltering. Alternate fuels are now awkwardly expensive and do not compete well with oil.

Natural gas, oil's sister with a cleaner reputation, has followed a similar pricing path with equally fearful symmetry. High natural gas prices led to spikes in electricity bills but spurred vast wind energy farms. Low natural gas prices weaken the rationale for wind.

Consumers, naturally, tend to follow the least expensive path. High gasoline prices made buying a hybrid a virtue. Low prices have sent buyers elsewhere, even as crippled car companies struggle to make more fuel-efficient and alternate-fuel vehicles.

For the third time since the 1973-74 oil price shock, a price collapse threatens to erase our determination to use less oil.

Federal mandates have pushed ethanol's share in the nation's transportation fuels supply above 10 percent. That's good news for reducing our dependence on foreign oil.

The bad news is that falling demand and falling oil prices mean those mandates could actually raise prices at the pump by 10 cents to 25 cents a gallon over the next two to three years, according to an analysis by the Washington- based Energy Policy Research Foundation.

The price slump also threatens massive investments in new oil production that were feverishly sought by the governments of the United States and other oil- consuming countries less than a year ago to stave off the day when demand exceeds supply.

Crude oil was selling for more than $145 a barrel as recently as July. Natural gas was selling for $14 per million British thermal units. Now oil is below $40 a barrel, while natural gas is hovering near $4 per million Btu.

The consequences of this rise and fall are evident in the number of drilling rigs working in Texas. In October, there were 935 rigs exploring for oil and natural gas. Last week, there were 564 – a decline of 40 percent in just four months.

The volatility of oil and natural gas prices last year was fed by speculation divorced from the realities of supply and demand. They're being driven down now by an economic crisis that's taken them well below the demand destruction caused by last year's high prices.

Breaking this fearful symmetry requires breaking the volatility of prices.

A long-term surplus of supplies would do it, but that seems unlikely with oil. An oil producer with deep pockets such as Exxon Mobil Corp. can press on with investments in supply, following a strategy that ignores equally the lure of very high prices and the repulsion of very low ones.

Other energy companies – whether they're looking for oil and natural gas or their alternatives – lack that freedom. Investing in the face of price volatility on this scale requires a lot of guts.

Or a deep-pocketed partner. Last week, China made big deals with Russia and Brazil that guarantee large volumes of oil on long-term contracts in exchange for billions of dollars in investment loans.

The deals should enable Russia's Rosneft and Transneft to ignore price volatility and press ahead with oil fields and pipelines from Siberia to China. They will help Brazil's Petrobras carry on with expensive investments in oil fields deep in the Atlantic.

China, in turn, assures itself of future oil supplies at what could be bargain prices.