Examples of harmony? Recently my chess tutor used a word which in hindsight is very interesting: harmony. He mentioned I should not just develop my pieces in the opening, but develop them harmoniously. Since then, I've noticed this word pop up again and again in various books. At the time, I took it to mean "make sure they are defending each other and working toward a common and well-defined goal", but I didn't really press for clarification.

Of course, in our next lesson, I'm going to ask him about this, but in the interim, I am hoping you can give your favorite examples of harmonious positions/development, as well as non-harmonious positions/development, including why they are harmonious/non-harmonious. In particular, is my above understanding of harmony correct or is it sometimes more subtle than that?
Admittedly, it's hard to make general abstract statements of any kind about chess (e.g. to say what "harmonious play" means) as it is a highly complex and concrete game. So everything said about it must be taken with some grain of salt, and with that in mind, here are some thoughts that will hopefully help you: 

Let's draw an analogy with music: (-> used for synonym here)


harmony -> consonance -> unison of notes


Somewhat similarly in chess this sequence translates into:


harmony -> consistency -> synergy of pieces


Consistency: "Having a bad plan is better than having none" by Yasser Seirawan (I'm paraphrasing). This quote really captures the essence: you need to have a strategy planned out which gives your play a sense of direction, otherwise your pieces would be moving around purposelessly all over the board which ultimately leads to redundancies (lost tempi), self-induced weaknesses, low value pieces (non-optimally developed), and so on. So always try to play with a plan in mind, as far fetched as it may seem, and make your decisions in consistence with that plan. 

Now to clarify what strategy entails here, one would have to put it into context, but in general it goes without saying that it takes into account not only what you plan to achieve but also what your opponent is aiming for, so it's always adaptive. A strategy/plan in the opening and middlegames could be anything, for instance:


Establishing a minor piece on a certain square - e.g. knights on permanent posts. 
A queen-side, central or king-side pawn expansion - e.g. sharp Sicilian type of positions
Forcing the trade of a bad piece - e.g. the caged c8 bishop in many queen's pawn games
Pawn breaks: plans to open up the game by undermining/challenging an advanced pawn (chain) - e.g. e5 - c5 type of breaks in many queen's pawn games again
Gaining control over an open file or diagonal - e.g. being a tempo up in doubling your rooks and claiming the open file. 
Enabling a certain piece - e.g. fianchetto'ed bishops.
the list goes on.


Synergy: or more simply coordination, means how to collectively coordinate your pieces towards achieving your planned strategy, after all chess is a team sport among your pieces. Given a target in mind, having a good coordination means you're enabling the right pieces efficiently (minimal tempi investment) while countering your opponent's preventive pieces of that plan. Slightly unlike strategizing, achieving a good coordination requires concrete (calculating actual lines) and tactical (using all the resources in the position) assessment of the position at hand. 

So synergizing your pieces in accordance to a plan/strategy can be labelled as harmonious play. Harmony is precisely what opening theory provides us: openings revolve around very clear ideas (take any opening: Sicilian, Benko gambit, Nimzo, ...) and in a way provide also the recipes for how to achieve those ideas (concrete lines and side-lines). So learning from them you can form a mindset for how to develop your pieces harmoniously.

Now some examples: (in what follows I'll be mainly focusing on a schematic analysis of the ideas, as opposed to a purely concrete one). 

Example #1: Sicilian Najdorf, in this example white's main plan revolves around (i) establishing a minor piece, preferably a knight, on the permanently (cannot be challenged by pawns) weakened d5 square (ii) while not allowing black to expand on the queen-side. Once can argue that (ii) is in fact a side-plan that actually enables (i), as you will see later in the game.
Coordination: To achieve (i) we need to remove the defenders of that square (d5), namely the f6 knight and the potential e6 bishop, develop or re-route the knights so they can simultaneously eye d5. The two defenders will have to be negated by our bishops (Bg5 for f6 and Bc4 for Be6). (ii) on the other hand, is achieved by a timely a4-a5 push, to permanently stop black from establishing a pawn on b5 or a knight on b6, nor even allow them to semi-open the b-file  with b6. (Diagrams annotated with additional remarks): 

 [title "M. Vachier-Lagrave vs I. Nepomniachtchi 1-0, Sinquefield Cup 2017"]
 [fen "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]

 1. e4 c5 2.Nf3 d6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 a6 6.Be2 e5 {First critical moment: Black has finally made their intentions clear with a very committal e5 - all e6 or g6 variations are irrelevant now} 7.Nf3 {Instead of Nb3 because white wants to be able to re-route to d5 either via c4-e3 or c4-b6} Be7 8.Bg5 {developing the bishop to immediately challenge the f6 knight guarding the d5 square} Nbd7 9.a4 {Stopping b5} O-O 10.Nd2 {Re-routing to c4 while waiting for the d7 knight to move before capturing on f6, we don't want to allow a knight recapture.} Nc5 11.Bxf6 Bxf6 12.Nc4 Be7 13.a5 {Completely stopping any b5 or b6 ideas with a5 and Nc4} Rb8 14.Nb6 Nd7 15.Ncd5 {with a5 critically re-enforcing b6, a knight on b6 and d5, black has no way of establishing a knight on either f6 or b6} Nxb6 16.Nxb6 Be6 {last resort to stop Nd5} 17.Bc4 {immediately challenged - notice the coordination between white's pieces up to this point, almost perfect!} Qc7 {Freeing d8 square to re-route the dark-squared bishop in order to capture the knight before landing on d5.} 18.Qd3 Bd8 19.c3 Qc6 {preparing Bxb6, note black doesn't mind recapturing with the f-pawn on e6 as that would provide black with some well needed light-square control} 20.Bd5 {important intermediate move: first pushing the queen away from the defense of d6 pawn, then capturing on e6 to force black to re-capture with the queen. These are all the tactical/concrete aspects we were talking about earlier.} Qe8 21.Bxe6 Qxe6 22.Nd5 {Mission accomplished: you can argue that white has already won the main strategic battle of the game.} f5 {an important pawn break: to primarily undermine the defense of d5 while also creating play on the king-side} 23.O-O Rc8 24.Rfd1 fxe4 25.Qxe4 Qf5 26.Qe2 Kh8 27.c4 {the knight in untouchable. In what follows we have a beautiful conversion of this positional advantage into a win.} Bh4 28.g3 Bg5 29.Ra3 Rce8 30.h4 Bd8 31.b4 Qg6 32.h5 Qf5 33.Ne3 Qe6 34.Rad3 Be7 35.Nd5 Bd8 36.Rf3 Rxf3 37.Qxf3 Kg8 38.Kg2 e4 39.Qe2 Qe5 40.Ne3 Bg5 41.Rd5 Qf6 42.Nf5 Re6 43.c5 dxc5 44.Qc4 Qf7 45.Rxc5 h6 46.Rc8+ Kh7 47.g4 Re7 48.Qd4 Re6 49.Qd5 g6 50.hxg6+ Kxg6 51.Rf8 Qxf8 52.Qxe6+ 1-0


Example #2: Catalan by Kramnik, a lot of the ideas in the Catalan revolve mainly around the g2 fianchetto'ed bishop, that is, we want to on the one hand, prevent black from finding ways to exchange our g2 bishop, and on the other hand, further enable the bishop by challenging the g2-b7 diagonal. The g2 bishop similar to the g7 bishop for black in the Benko gambit, is what gives us a sense of direction in our play. Now let's watch Kramnik in action:

 [Title "Vladimir Kramnik vs Anish Giri 2014 (1-0)"]
 [fen ""]

 1.d4 d5 2.c4 c6 3.Nf3 Nf6 4.Nc3 e6 5.g3 dxc4 6.Bg2 b5 7.Ne5 {Adding pressure on c6} a6 {There's a tactical idea involved here: white would be doing themselves a dis-favour if they took on c6 here, as 8.Nxc6 Qb6 9.Nxb8 Bb7 would actually enable black to quickly challenge the g2 bishop forcing an undesired e4, while having got rid of the c6 weakness} 8.O-O Bb7 9.b3 {challenging the light-square control, in order to prepare Nd3. Note that white's queen-side pawns are often absorbed in challenging black's queen-side pawn expansion in these types of positions} cxb3 10.axb3 Be7 11.Bb2 O-O 12.Qc2 Nfd7 13.Nd3 Qb6 14.Ne4 {both knights coordinating towards the control of c5 square: as long as we control c5 the c6 weakness stands for black, a clear target for white} a5 15.Ndc5 Bc8 16.Qc3 b4 17.Qe3 Na6 18.Rfc1 {immediately re-enforce c5 after black's renewed challenge.} Nc7 19.Nxd7 Bxd7 20.Nc5 Be8 {let's step back and look at the position: Both semi-open a and c files contain black back-pawns, the c5 control has completely disabled black from getting rid of the c6 weakness, with a passive bishop on e8 black has no means of challenging white's g2 bishop,... we can safely say: white has won the main strategic battle of the game.} 21.Ra2 Qb5 22.Qd3 {The rest is Kramnik's beautiful conversion of this clear positional advantage} Qxd3 23.Nxd3 Nd5 24.Ne5 Ra6 25.Bf1 Nc3 26.Bxc3 bxc3 27.Rxc3 c5 28.dxc5 Bf6 29.f4 Bb5 30.Bg2 Ra7 31.c6 Be7 32.Be4 f6 33.Nf3 Rd8 34.e3 e5 35.fxe5 fxe5 36.Rc1 a4 37.bxa4