The spiritus lenis ("soft breathing") or psilon pneuma (Greek: psiln, ψιλόν) is a diacritical mark used in Greek. It indicates the absence of initial aspiration: in other words that the word did not begin with an [h] sound in Ancient Greek. Some have assumed that it stands for a glottal stop, but Allen1 considers this "highly improbable". It is written as on top of or to the left of an initial vowel (the second vowel of a pair comprising a diphthong), and also in certain editions on the first of a pair of rhos. It did not occur on an initial upsilon. It takes the form of a closing half moon or a closing single quotation mark:
ἀ- ἐ- ἠ- ἰ- ὀ- ὐ- ὠ;
Ἀ- Ἐ- Ἠ- Ἰ- Ὀ- Ὠ.
It is part of the traditional polytonic orthography for Greek, but has been dropped in the modern monotonic orthography as the [h] sound has disappeared from Modern Greek. The origin of the sign is thought to be the right-hand half– ┤ –of the letter H, which was used in some Greek dialects as an [h] while in others it was used for the vowel eta.
The speed of the breathing is increased in accompaniment to the speed of the movements of the body.
Therefore it is noticed that the breathing is smooth or quiet, when there is no bodily movement or when it is in its normal or relaxed state.
After having such smoothbreathing for some time, the movements of the abdomen and the lungs should be brought under the control of the mind, and the movement should further be slowed.
The spiritus asper ("rough breathing"), dasy pneuma (Greek: dasu, δασύ) or dasia (Greek: δασεῖα), is a diacritical mark used in Greek.
When a word begins by an initial grapheme which is a vowel not preceded by an [h], the spiritus lenis ("soft breathing") is employed.
It is part of the traditional polytonic orthography for Greek, but has been dropped in the modern monotonic orthography as the [h] sound has disappeared from Modern Greek.