What's a good bible on vegetarian cooking?

I'd recommend Mark Bittman's "How to Cook Everything Vegetarian", I use it all the time. It's certainly what I would call comprehensive; besides containing tons of recipes for everything from entrees to breads to soups, the sections are prefaced with tips on how to improvise or switch up the recipes as desired, including vegan alternatives.

I would say that Madhur Jaffrey's World Vegetarian, with 650+ recipes, has been a source of great inspiration for me. It's comprehensive and boasts a great number of different styles and ingredients.

Additionally it's informative, offering a lot of history about the foods, the places they have come from and the people who developed them. It strengthens the "I want to go [more] meatless" mindset for everyone I've ever spoken with.

Not to mention she has won a number of James Beard Awards and she is Indian, giving her some great insight into that particular culture.

The book itself is fairly inexpensive over at Amazon too. Good luck!

The Moosewood Cookbook, by Mollie Katzen, is often regarded as a sort of bible of vegetarian cooking. It's one of the best-selling cookbooks ever, not just among vegetarian cookbooks, and helped show Americans that they didn't always need meat to make good food. The original is from 1977 and may be harder to find, but there's a revised version, The New Moosewood Cookbook. The recipes are generally pretty simple, amenable to substitutions and alternate versions, and the style is very friendly. It should have things for every season - she wrote the original while at the Moosewood Restaurant, whose menu changes daily based on what's available. The author has plenty of recipes on her website, which should give you a good idea of the style and types of recipes. If you like it, she's written several other cookbooks as well!

Note: As lemontwist points out, there's fish in some of her books. But there's plenty even without those recipes; just think of it as some added stuff you'll never make if you're actually vegetarian.

Bittman's How to Cook Everything Veg I second. He's very good at explaining the basics and rarely disappoints. I'd also have to add in the "must have" category, Sundays at Moosewood, which is a collection of international veg recipes, some of which are delicious--African Groundnut Stew over millet... Sounds exotic, but its components are basic: regular root vegetables with a tangy-fruity peanut sauce. I realize this isn't close to a Joy of Cooking or Julia Child, but once you have the basics down, you'll want a book containing a variety of foods and flavors. The old classic Laurel's Kitchen has a great introduction, nutritional info., basic recipes, and a very homemade/homespun bent, even if it is decades old. Ditto the Vegetarian Epicure. Probably there isn't one bible but maybe a collection of 5 recipe books. Post Punk Kitchen is a great vegan resource: ppk.com. Also, Heidi Swanson's 101cookbooks.com. Many of these fit the bill you outline above re: some quick recipes, some slow, regular ingredients, weekday meals... Another excellent addition is the Candle Cafe Cookbook, which is vegan. I could live out of that thing year round. Mayonnaise only WISHES it could hold a candle to their vegan mayo recipe! It's that good.