Introduction : exploring the principles of embryo creation -- It's all in the genes -- How an embryonic cell "decides" its future destiny -- How cells talk and listen to each other -- How do simple modules lead to complex patterns? -- How can a single substance generate multiple responses? -- How do patterns evolve rapidly? -- How are cells programmed to follow predictable routes to specification? -- Ensuring that embryo development is on the right track -- Shaping the tissues -- Stem cells -- What's next?