These are i)active virtues, ii) passive virtues, iii) private virtues, and iv)public virtues.
If a person exerts himself to make others tread the path of virtues and actively resists evil, he is said to follow active virtues.This type of virtues is extolled by Zoroastrian religion.
If a person is honest,just and truthful and rests satisfied with his virtuous life, he is said to follow passive virtues.
Private virtues are those which make a person's private life happy, for example married life,contentment,simplicity,frugality.
Public virtues are those which benifit a large number of people,for example courage,bravery,generousity,public spirit to fight for truth and justice.
To act against moral principles is considered a sin - All acts of sin slow down soul's progress towards perfection and they are a heavy burden on mind.
Sins are classified as i) Sins of commission and ii) Sins of ommission. If a person performs an evil action knowingly it is a sin of commission, but if a person knowingly avoids an oppurtunity to perform a good deed it is a sin of ommission.
To repent is to retract from sin and return to the path of virtue.
Through repentance a person gives expression to his suppressed thoughts and feelings and thus lightens the burden off his mind.Sincere repentance before God helps man cease from sin.
One can repent of one's sins in three ways i) repentance through thoughts (Paititem mano) ii) repentance through words (Paititem vacho) and iii)repentance through deeds(paititem shyaothnem)
The four natural elements fire,air, water and earth enter into the composition of human body,hence on their purity depends the general health of mankind.Also, the four natural properties in human body viz. heat,moisture, coldness, and dryness are derived from those four elements.
It is observed by not burning dead and decomposed matter on fire,nor throwing it into water,nor interring it in earth.
It is exposing a dead body to birds on the highest places.Also, on high open spaces sun-light and air act as very powerful purifying agents, and prevent decomposition from spreading around.
It is the most economical.Certain birds like vultures and ravens are meant specially for the purpose of devouring the corpses and carcasses, and they are called scavengers of nature.
All living beings have life-force to sustain them.This life force derives its strength from the food which is consumed.It is one of the teachings of the zoroastrian religion that nothing should be wasted.Thus, even a dead body is put to good use insofar as it is consumed by the carnivorous birds and strengthens their vitality.
Man's physical organism consists of physical body containing all the external and internal organs, and it is termed " tanu " in Avesta and there is also the bony skeleton called 'azda' supporting the fleshy part.To energize and vitalize the physical body heat and energy necessary, and the process of respiration called 'ushtaana' imparts vitality and life to the body.There is also the form of the body called 'kehrpa ' and strength to move about and will called 'tevishi'.
They are: i) Ahu or life, ii) Daenaa or conscience, iii) Baodha or intellect, iv) Urvan or soul, and v) Fravashi or guardian spirit.
Ahu is the active principle of life which has its abode in the heart,and vitalizes all senses of perception.
Daena is the inner voice of conscience which guides one while performing actions which will ultimately determine one's future state.
Baodha or intellect reacts to the impulse carried to the brain centre through sensory nerves, which reaction is carried back to the sense organs through motor nerves and perception results.