It is never too early in a course of music study to consider the requirements of musical expression.  Persistent observance of them will inevitably quicken the artistic sense.  The rules to which they have given rise are for the most part simple and easily explained.  For obvious reasons, all musical interpretation is expected to imitate song as closely as possible.  The human voice, the primitive musical instrument, in moments of excitement, ascends to a higher pitch, increasing in intensity of tone as it sweeps upward.  Consequently every progression from lower to higher tones, whether played or sung, demands a crescendo unless some plainly denoted characteristic of the music calls for different treatment.  A descending passage, as a return to tranquillity, requires a decrescendo.

“The outpouring of a feeling toward its object, whether to the endless heavens, or forth into the boundless world, or toward a definite, limited goal, resembles the surging, the pressing onward of a flood,” said the great teacher, Dr. Adolph Kullak.  “Reversely, that feeling which draws its object into itself has a more tranquillizing movement, that especially when the possession of the object is assured, appeases itself in equable onward flow toward the goal of a normal state of satisfaction.  The emotional life is an undulating play of up-surging and subsidence, of pressing forward beyond temporal limitations and of resigned yielding to temporal necessities.  The crescendo and decrescendo are the means employed in music for the portrayal of this manifestation of emotional life.”

Another important matter which may to a great extent be reduced to rule is that of accentuation.  Through it a tone-picture is invested with animation, and a clue is given to the disposition of tonal forms.  Accents are always required to mark the entrance of a theme, a phrase or a melody.  Where there are several voices, or parts, as in a fugue, each voice denotes its appearance with an accent.  Every daring assertion hazarded in music, as in speech, demands special emphasis.  Dissonances need to be brought out in such prominence that they may not appear to be accidental misconceptions, and that confident expectation may be aroused of their ultimate resolution.  Accentuation must be regulated by the claims of musical delivery.  At all times too gentle an accent is without effect, too glaring an accent is to be condemned.

Hans von Buelow strenuously advised young musicians to cultivate their ears and strive to attain musical beauty in what is termed phrasing, which he regarded as the real beginning of greatness in a performer.  Phrasing and time keeping are two of the prime essentials in musical delivery, and cannot be neglected with impunity.

Time may well be called the pulse of music.  Upon some occasions the pulse beats more rapidly than others.  It is incumbent on the interpreter of music to ascertain the harmonic and other causes which determine the tempo of a musical composition, as well as those which make slight variations from it admissible.  Among other points to be noted is the fact that sudden transition from repose to restless activity calls for an accelerando, while the reverse requires a rallentando.