It is a great profession. There is the fascination of watching a figment of the imagination emerge through the aid of science to a plan on paper. Then it moves to realization in stone or metal or energy. Then it elevates the standards of living and adds to the comforts of life. That is the engineer's high privilege.

When my father, Igor Sikorsky came to Paris in 1909 to study aviation, he has a letter of introduction to a great French aviator and pioneer pilot, Captain Ferdinand Ferber. The good Captain gave the twenty-year old Igor Sikorsky much valuable advice during their first meeting. When that meeting ended Ferber's last words of wisdom, roughly translated, were as follows: ''...To invent a flying machine is nothing; to build it is little; but to make it fly....Ah, that is everything!''

Shall I refuse my dinner because I do not fully understand the process of digestion? Oliver Heaviside (according to von Karman and Biot)

What I am about to say on the phenomena of turbulent flows is still far from conclusive. It concerns, rather, the first steps in a new path which I hope will be followed by many others. The researches on the problem of turbulence which have been carried on at Gottingen for about five years have unfortunately left the hope of a thorough understanding of turbulent flows very small. The photographs and kinetographic pictures have shown us only how hopelessly complicated this flow is.... Ludwieg Prandtl (1926) ''Turbulent Flow'' NACA TM 435. Originally delivered to 2nd Intern. Cong. Appl. Mech. Zurich, 1926.

First get on in any way possible and let the logic be left for later work. Oliver Heaviside

Turbulence is an irregular motion which in general makes its appearance in fluids, gaseous or liquid when they flow past solid surfaces or even when neighbouring streams of the same fluid flow past or over one another. G. I Taylor, according to von Karman (1937). Twenty-Fifth Wilbur Wright Memorial Lecture entitled ''Turbulence.''

Turbulent fluid motion is an irregular condition of flow in which the various quantities show a random variation with time and space coordinates, so that statistically distinct average values can be discerned. Hinze

The term `turbulent flow' was not used in those earlier studies; the adjective then used was `sinuous.' The term `turbulent flow' was introduced by Lord Kelvin in 1887. Cebeci and Smith

Big whorls feed on little whorls, and so on to viscosity.

You can't steer a stationary car.

We must measure what is measurable and make measurable what cannot be measured.

When I was a student, I read everything. When I was a young faculty member, I read everything in my area of interest. Now I only have time to read papers sent to me for review.

The current of our thoughts made as sudden bends as the river, which was continually opening new prospects to the east or south, but we are aware that rivers flow most rapidly and shallowest at these points.

Altissima qu¾que flumina minimo sono labi (The deepest rivers flow with the least sound).

It must not remain our desire only to acquire the art of the bird, nay, it is our duty not to rest until we have attained to a perfect scientific conception of the problem of flight, even though as the result of such endeavours we arrive at the conclusion that we shall never be able to transfer our highway to the airÉTherefore let us investigate in a truly scientific spirit, without preconceived notions as to the nature of birdflight, its mechanism, and the conclusions which may be derived from it.

What the exact significance of all this complication [in bird wing design] may be, presenting so marked a contrast to the uniform curves of an aeroplane, it is difficult to say. Probably there is some significance, since in birds that are strong on the wing the whole mechanism of flight down to minute details is so efficient.