After visiting school and higher education, he graduated in 1966 at the University of Amsterdam in astrophysics and mathematics; his graduate research was in numerical analysis and programming for celestial mechanics. In the same year, he started working at the mathematics department of the Technological University of Delft, where he spent his time on teaching, research, management and politics. This period was also the beginning of his interest in engineering problems. During these years, he lived with his wife and three kids near Delft in a windmill, dating from 1637.

Realising that getting back to basics, that is, doing research, was necessary, he gave up his permanent position and moved in 1971 to the department of mathematics of the University of Utrecht, where he became a PhD student of

In the seventies, exciting developments in applied mathematics were the theoretical analysis and numerics around the KAM theorem in Hamiltonian mechanics and the many new results in the analytic foundations of asymptotic analysis. His research papers and books reflect his interest in both fields.

Starting in 1969, he visited regularly East European conferences, first from curiosity, but increasingly from a feeling that ``something had to be done'' about this unnatural split of Europe into two parts. These visits triggered cooperation with East European colleagues that are continuing until today.

As usual, he held a number of administrative positions; for instance, he chaired for several years the Foundation which ran the University of Utrecht Weekly. This stimulated his interest in the media and in communicating science. In 1985 he founded a publishing company, Epsilon Uitgaven, which publishes science books, in particular mathematics books, in Dutch.

For nine years he was an editor of SIAM Journal on Applied Mathematics. He is still an editor of the Journal of Nonlinear Science, Zeitschrift f. Angewandte Mathematik und Mechanik, Nonlinear Dynamics, SIAM series on Classics in Mathematics, Epsilon Uitgaven (managing editor), Zebrareeks.

Mathematics is an international affair and doing mathematics research has entailed many visits and good contacts all over the world. Listing the visits, lasting at least a month, these were (with the host between brackets): Imperial College, London (

Finally a word about ancestors. In 1625, ancestor *Willem Verhulst*,
established and directed a settlement on
the island Manhattan. His directorship was not very successful and
the Verhulst
family has little control over the island nowadays.

Another family relation, *Pierre Francois Verhulst*, is further removed in
the family tree. Around
1570, when the war between the Dutch and the Spanish Empire started, this part
of the Verhulst
family was sidetracked to stay in the Southern Netherlands, now Belgium. Pierre
Francois
became a specialist in elliptic functions and invented around 1850 the
post-Malthusian
logistic equation.