Eggs and early embryos are programmed to undertake particular developmental decisions at characteristic times, but precisely how these decisions are timed has long remained elusive, whereas an increasing number of studies recently focus on timing. The paper to be introduced this time, published early in the year 2000, discusses the possible roles and interactions during early vertebrate development of two broad categories of timers, one involving cyclic or sequential mechanisms ('clocks') and the other one requiring an increase or decrease in some factor to a threshold level for progression of time ('hourglass timers'). Remarkably, the paper, published as a 'review', includes only two conceptual figures and no original data. Using this paper as an example, various routes for disseminating new ideas and hypotheses, as well as the biological contents of the paper, will also be discussed.