7 i972 ACM Tearing Award Lee~ture glossary can possibly indicate. The sophical addresses at ~>~p,~ his aL tatio~ read 6y M~D. Mcllroy, chair-, precious gift that this Turing Award ready classic papers on cooperating e,lan o/l/~e A CM Tz~rit,g A ward Cot~> ack,~owledges is Dijkstra's slyle: his sequential processes, ~ and his mem~ *nitgee, at tt~e preset~taKot, o/ tkks' approach to programming as a high, orable indictment of the go-to state- lect~re <~t~ Au,g,~c,t 14, t972, at the intellectual challenge; his eloquent rnent/An influential series of letters A CM A ~m~at ('o~jere~ce in Bos'ton.] insistence and practical demonstra- by Dijkstra have recently surfaced as The workiug vocabulary of pro- tion that programs should be corn-. a potished monograph on the art of grammers everywhere is studded with posed correc@, not just debugged composing programs/" words originated or forcefully prom- into correctness; and his illmninating We have come to value good pro- )/ ulgated by E,W. Dijkstra-display0 perception of problems at the foun- grams in much the same way as we deadly embrace, semaphore, go-to- dations of program design. He has value good literature. And at the less programming, structured pro- published about a dozen papers, both center of this movement, creating and gramming. But his influence on pro- technical and reflective, among which reflecting patterns no less beautiful grammiag is more pervasive than any are especially to be noted his philo- than useful, stands E.W. Dijkstra. The Humble Programmer by Edsger W. Dijkstra ~,~ ~i~!il~ s '(;:ziii:i!!i; As a result of a long sequence I was supposed to study theoretical of coincidences I entered the pro- physics at the University of Leiden gramming profession officially on the simukaneously, and as I found ~he first spring morning of 1952, and as two activities harder and harder ,to far as I have been able to trace, I combine, I had to make up my was the first Dutchman to do so in mind, either to stop programming my country. In retrospect the mnst and become a real respectable theo- amazing thing is the slowness with retica~ physicist, or to carry my study which, at least in my part of the of physics ~o a formal completion world, the programming profession only, with a minimum of effort, and emmlged, a slowness which is now to become.,,, yes what? A pro- hard to beiieve, But I am grateful for grammer? But was ~ha~ a respect- ) ~.!;i!!:iii~ two vivid recollections from that able profession? After all, what was period that establish that slowness programming? Where was the sound beyond any doubt. body of knowledge" that could sup- After having programmed %r Copyright © I972, Association for Compu*ieg Machinery, Ir~c, Generaf per~ some three years~ I had a discussion missio~ ~o ~xep~JbF.sh, bus ~mt for profit, with van Wijngaarden, who was then all or part of ~his maa~qa/ is groined, my boss at the Mathematical Centre provided ~hat referenda: is made ~o this publica~km, to [~s date of ~ssue, and ~o in Amsterdam-a discussion for the fact %a~ reprinti~g 1~rlvileges were which 1 shall remain grateR~l ~o him gray,ted by ~rmi:ssioa of the Association! %r Compu@~g Mad@~ery. as toeg as l live, The point was that /2J~.~ Foo[no~.e8a~'e o~'t page 866~ 859 Corn ~a~1~ i¢~a !iiorls ©ctob~r ~972 of Val~m~e 15 the ACM N~amH~r t0 port it as an intellectually respectable don today. White we pursue our cance, and also because it was pat- discipline? I remember quke vividly analysis, we shall see how many endy obvious that this machine would how I envied my hardware cob common misunderstandings about have a limited lifetime, he knew ~ha, leagues, who, when asked about their the true nmure of the progranmfing very Httb of his work would have professional competence, coukt at task ca~ bc traced back to that now a lasti~G value. Finally, there i~ least point out that they knew every- distartt past. yet am~thcr circumstance that had u. thing about vacuum tubes, amplifiers The first automatic electronic profound influence ou the program- and the rest, whereas I fek that. computers wcrc ali unique, singie- reef's attitude toward his week: on when faced wida that questio~, I copy' machines and @e~ were all to the one hand, besides being unre- would stand empty-handed, Full of be found in an e~wiromnent wkh tiabk', his machine was usually too misgRings t knocked on ',an %i.jn- the exciting fla~or of an experimental slow and its memory was usually gaarden's office door, asking him laboratory. Once @e ',ision of the too small, i.e. he was faced with whether t could speak to him for a automatic computer was @ere. its a pinching shoe, whib on the o@er moment; when I left his office a realizado~ was a tremendous chair hand its usually somewhat queer number of hours later, I was an- lunge to the cbctronic technology order code would cater for the most other person. For after having Hs- then a,,ailable, and one thing is cur- unexpected constructions. And in tuned to my problems patieud3, he tam: ',~e cannot deny the courage @ose clays many a clever program- agreed that up till tiaat moment there of the groups that decided to t O to met derived an immense hucltectual was not much of a programming build such a fantastic piece of equip- satisfaction from the cunning tricks disciplin< but then he went on to taunt. For fantastic pieces of equip- by means of which he contriveci to explain quiedy @at automatic com- ment they were: in rdrospect one squeeze the impossible into the cou- puters were here to stay. that we can only wonder that those first ma- straints of his equipment. were just at the beginning and could chines worked at all, at least some- Two opinions about program- not I be one of the persons called times. The overwhehning probbm ruing date from those days. t men- to make programming a respectable was to get and keep the machine in tion them now; [ shall return to discipline in the years to come.' This working order. The preoccupation them later. The one opinion was that was a turning point in my life and with the physical aspects of auto- a really competent programmer I completed my study of physics matic computing is still reflected in should be puzzle-minded and very formally as quickly as I could. One the names of the older scientific so- fond of clever tricks; the other opin- moral of the above story is, of cieties in ~he field, such as the Asso- ion was @at programming was noth- course, that we must be very earefut ciation for Computing Machinery or ing more than optimizin~,.~~ the effi- when we give advice ~o younger the British Computer Society, names cier~cy of the conputational process, people: sometimes they follow it! in which explicit reference is made in one direction or the other. Two years later in 1957, I mar- to the physical equipment. The latter opinion was the result fled, and Dutch marriage rites re- What about the poor program- of the frequent circumstance that, quire you to state your profession mer? Well, to tell the honest truth~ indeed, the available equipment was and I stmed that I was a program- he was hardly noticed. For one thing, a painfully pinching shoe, and in mer. But. the municipal authorkies the firs~ machines were so bulky that those days one often encountered of @e town of Amsterdam did nor you could hardty move them and the naive expectation that, once more accept it on the grounds thus there besides that, they required such ex- powerful machines were available, was no such profession. And, be- tensive maintenance that it was quite programming would no longer be a lieve it or not, but under the head- natural that the place where people problem, for then the struggle to ing ~proflossion" my marriage record tried to use the machine was the push the machine to its limits would shows the ridiculous entry *{heo~ same Iaboratory where the machine no lor~ger he necessary and that was retical physicist"! had been devdoped. Secondly, the all that programming was abouL So much for the slowness with programmer's somewhat invisible was[ft it'? But in the next decades which I saw the programming pro- work was wid~out any glamour: you something completdy different hap- fession emerge in my own country. could show the machine ~o visitors pened: more powerful machines be- Since then I have seen more of the and tha~ was severai orders of map came available, not just an order world, and it is my genera1 impres- nitude more spectacular than some of magnitude more powerful, even sio~ that in other countries, apart sheets of coding. But most important several orders of magnitude more from a possible shift of dates, the of nil ~he programmer himself had powerful, But instead of finding our- grow@ pattern has been very much a very modest view of his own work: salves in a state of eternal bliss with the same. his work derived all its significance at1 programming problems solved, Let me try to capture the si~ua~ from the existence of ~hat wonderful we found ourselves up to our necks tion in those old days k~ a ti@e bit machine, Because that was a unique in the sohware crisis! How come? more detait, in the hope of getting machine~ he knew only {oo well that There is a minor cause: in one a better understar~diag of the siR~a.~ his programs had only local signifi- or two respects modern machinery Con}m~.micatior~s October I972 off Volume ~5 1be ACM Nt~mber t0 !~/ ! iS hasicuIly more difficult to haI~dlc trouble with minor prophets° of design cannot have been that bad.