LETTER TO THOMSON 183 



are simply enunciated in the R. S. E. paper, become 311 and 312. 

 Tait nicknamed these theorems Greed and Laziness, namely, 



(1) Greed: Given any material system at rest, and subjected to an 

 impulse of any given magnitude and in any specified direction, it will move 

 off so as to take the greatest amount of kinetic energy which the specified 

 impulse can give it. 



(2) Laziness: Given any material system at rest. Let any parts of 

 it be set in motion suddenly with given velocities, the other parts being 

 influenced only by their connection with those which are set in motion, 

 the whole system will move so as to have less kinetic energy than belongs 

 to any other motion fulfilling the given velocity conditions. 



The postscript indicates that there was still some hope of publishing 

 the more elementary book before the other. 



The following letter touches on a variety of subjects more or less con- 

 nected with the book : 



6 G. G. E. 



24/4/63- 

 Dear T., 



I have been working up my Quat. article for Proc. R. S. E. I find that 

 in your " Mechanical Representation of Electric etc. Forces " you need never have 

 taken the rotations of the solid you can always get displacements suiting any of 

 the forms of force, and they are in fact simpler than yours as given in the Math. 

 Journal. I will send you a proof to-morrow so that you may advise on it before it 

 goes to press. 



The whole mystery of Electromagnetism lies in the operator 5 + \ V, as I 

 pointed out to Sir W. R. H. four years ago but I cannot get a closer insight, at 

 least at present.... 



Also Stewart and I have simultaneously struck on an idea of which "Conserva- 

 tion of Energy" is a particular case and we intend to develop from it some 

 tremendous consequences numbers of which have already been booked and talked 

 over. A third volume of the book will be required for it, if it do not in fact 

 destroy the necessity for the first two. It is a gushing, gasping, idea. But, more 

 anon. As it will at once obliterate everybody who pretends to science but is not 

 acquainted with it, we propose shortly to initiate you, in order that you may not 

 be lost in the stramash that will follow its publication. 



Gray promised me Sheet 7 (with the cuts) to-night but it has not come yet, 

 and of course won't to-night. Look out for it on Monday. 



Also look sharp to Chap. II for I have no doubt you see the propriety of 

 putting Sph. Hares. & Quatns. in an appendix at the end of the Vol. 



Ponder this. 



In Statics and Kinetics we should in the large volume keep to general theorems 



