The dominant seventh may be used in any but its second inversion, the fifth being omitted.[2] The seventh requires no preparation.  Other chords of the seventh are better not used until second species and later.

If possible, let the chord in the first measure appear complete.  The last chord but one should be complete, unless some form of V or V_7 is used. [Fig. 89.]

[2] In severely strict counterpoint all parts above the lowest must be consonant with it.  Dissonances, when entering simultaneously with it, must be treated as suspensions, and when used in the progression of a part from one chord to another, should be treated as passing-tones or embellishments.  This excludes the use of the unprepared seventh and ninth; all diminished and augmented triads except in their first inversion; and all six-four chords, except when the lowest part is treated as a passing-tone.

[Illustration:  Fig. 89.]

Consecutive major thirds may be used when three or more parts are employed. [Fig. 90.]

[Illustration:  Fig. 90.]

A note may now be repeated in the lowest part when it becomes the seventh of a dominant seventh-chord. [Fig. 91.]

[Illustration:  Fig. 91.]

In writing, use soprano, alto and tenor, or alto, tenor and bass; and do not separate upper parts more than an octave.  For a chord or two they may (for the sake of better voice-leading) separate a tenth.

All hidden fifths and octaves are bad, except between I and V and V and I. [Fig. 92_a, b_.]

The perfect fifth following the diminished fifth is good when taken in an upward direction stepwise in the higher parts. [Fig. 92_c_.]

[Illustration:  Fig. 92.]

All cadences used in harmony are good.

Unless otherwise mentioned, put the cantus firmus in any part, but avoid its continued use in the same part.

EXERCISES

To canti firmi a and b write the first species in all parts.  Write each three times, setting the cantus firmus in a different part in each solution.  This necessitates transposing the cantus firmus, when setting it in the other parts.

CANTI FIRMI

[Illustration:  Fig. 93.]

LESSON XII

THE SECOND SPECIES

[Illustration:  Fig. 94.]

The second species is written in one part and the first in the other two.

All suggestions made for the second species in two-part counterpoint are to be observed, unless otherwise mentioned.  Those regarding consecutive perfect intervals are especially to be observed.

The fifth, when in the lowest voice, should be used as in two-part counterpoint, except when used in V4/3 or the cadencing tonic six-four chord.

The V4/3 chord may be used on the weak beat, necessitating the omission of the third. [Fig. 95_a_.]