The Bible took a pessimistic view of reaching 70. "Our years are threescore years and ten," it said, "and though some be so strong that they come to fourscore years, yet naught is their strength then but sorrows and abundant labour".
But now we are more sanguine. Seventy is a mere milestone on the now much longer road of life, and a time to celebrate juventus senectutis. It is an occasion for a party, and that is just what his friends have organised for William Arthur Watts.
Prof Watts of TCD is a botanist of worldwide reputation. His particular interest throughout his long career has been what we know as palaeoecology, the study of nature in the dim and very distant past.
To celebrate his 70th birthday his colleagues have organised an international symposium on the theme "From Palaeoecology To Conservation: An Interdisciplinary Vision". It will begin at 7 p.m. tomorrow at the Royal Irish Academy in Dawson Street, Dublin, and continue through the following day.
The gathering will focus on the fact that for a significant part of the past million years or so, Ireland was not the green and pleasant land we know today but a barren waste, languishing for much of the time under several hundred feet of ice. In between were interglacial periods with more benign conditions, similar to those which we enjoy today.
The climates of those distant times have left footprints on the sands of time. Layers of sedimentary rock, for example, contain pollen which shows the range of vegetation at the time they were laid down, and buried fossils indicate the insect life.
Even prehistoric human remains, uncovered in bogs, have on occasion been so well preserved that it has been possible to analyse and identify the contents of the stomach - and, of course, local foods are indicative of local weather.
The keynote address on "Reconstructing Past Environments from the Quaternary Palaeovegetation Record" will be delivered tomorrow evening by Prof Brian Huntley of the University of Durham. Other talks on Thursday include Dr Eric Grimm of Illinois on `Vegetation and Climate Change on the Northern Great Plains of the United States", John Lowe of the University of London on "Climate Behaviour in the North Atlantic and Europe During the Last Glacial-Interglacial Transition" and Pete Coxon of TCD on "Understanding Irish Landscape Evolution: the Use of Palaeoecology, Biostratigraphy and Biogeography".
Do you find them intimidating, these sesquipedalia verba, the foot-and-a-half words that Horace used to talk about? If not, and if you would like to go to Prof Watts's birthday party, ring Pauric Dempsey at the RIA.