Square of stops

The Square of stops is an arrangement of a group of nine Greek sounds which are all "stops", that is, made by the momentary stopping of airflow at some place in the mouth. The sounds are arranged according to how they are made: where the stopping of airflow takes and the characteristics of the airflow.

When the letters σ and θ come up against a stop, the pronunciation can be awkward and so the spelling changes a little to make it smoother. The square of stops is a memory aid and a useful device for predicting how such spelling changes take place. This is applied, for example, in forming verbs in the future tense which involve the tense formative σ.

Explanation of terms:
 * Labial - the airflow is stopped with the lips
 * Velar - the airflow is stopped at the upper palette with the back of the tongue
 * Dental - the airflow is stopped at the teeth with the help of the tongue
 * unvoiced - the sound is not made with the vocal cords - place you fingers against the vocal cords when you make the sound and you will not feel them vibrate
 * voiced - the sound is made with the vocal cords - you can feel them vibrate
 * aspirated - the sound is made with a large puff of air

Examples

 * βλέπω (I see, present tense) -> βλεπσω (insert future tense formative) -> βλε(π + σ = ψ)ω (apply square of stops) -> βλεψω (I will see, future tense)