This issue sees the launch of two series of essays, devoted respectively to writing and concepts in science. It also contains an unusual collection of overviews in the Insight section which focuses not on the current state of research but, in a more visionary spirit, on its future (see page 385). All of this represents an effort to focus on aspects of the essence of science, rather than on new results or new developments in science policy. And at some level, all focus on something the literature sees too little of: scientific ideas.

The self-censorship of ideas from scientific journals is, up to a point, desirable. The value of ideas as perceived by others (including referees) can be highly subjective. Few have the time to invest in the hope that an idea has potential, only to find that it does not. And an idea's true originality can be difficult to evaluate. New ideas, in short, are usually best cultivated in private, especially if one wants to reap the rewards that their fulfilment might bring. And the literature is burgeoning enough already.

Nevertheless, open discussion of ideas seems undervalued. Occasionally, an old idea may deserve public re-examination because it has more to offer or is being misrepresented — as a result, perhaps, of the 'Chinese whispers' of second- or nth-hand citation. Or a recent idea may deserve explication to a wide audience to fulfil its potential between disciplines. Alternatively, an idea may deserve examination for its development.

It is with these considerations in mind that the series Concepts (see page 289) has been conceived. Some scientists niggle away at a concept for years, finding it an ever-fruitful source of stimulation or puzzlement. Some may be exasperated by others' perceived misuse of a concept. Either way, they have a point of view that deserves to be captured for the rest of us. Each article will therefore not only communicate some aspect of a concept to readers, but will also bring a touch of the author's personal perspective along with it.

The act of writing itself, in and about science, also deserves celebration and analysis. Hence our other new section, Words (see page 287). The weekly articles will explore issues, anecdotes and episodes (both historical and contemporary) that elucidate the relationship between science and words. We shall be publishing contributions from authors in the many disciplines that touch on science, words and language, including leading linguists, historians of science, poets, playwrights, novelists, anthropologists and scientists who are themselves excellent writers.

These articles are essays — a word defined by at least one dictionary as "a literary composition". We hope that, in both new series, the writing itself will be found to be as enjoyable as the messages are refreshing.