Why we say man from mars and women from venus ?

The old alchemic symbols for Mars and Venus (still used in astrology now) are the same symbols as for male and female, respectively. In mythology, Mars was the male god of war and Venus was the female goddess of beauty: this put them at odds with one another over almost every subject, so it is a good analogy for men and women viewing life differently. Jupiter and Saturn would have worked just as well (Jupiter was the "King" of the gods and Saturn was his wife who, likewise did not get along well), but the connection to the Mars and Venus symbols clinches the deal.

I think it's from the book of the same name. The ancient Greeks gave people characteristics based on certain gods - who were linked to certain stars. Later, we named these planets after their gods. The zodiac etc all rotates round this idea. Holsts "The Planet suite" was written to reflect the characteristics of each God linked to the planet named after him, rather than the planet itself. Anyonw who has read about Venus knows it's much closer to Hell than most suns are! However, from Greek tradition: Mars is a fiery warlike sign, Venus represents softness and motherhood. Most of the muthas on my estate are definitely Mars signs. The men are mainly aliens!

Venus is the Roman Goddess of Love and mars is The roman G-d Of war.So it is a way of saying women are more able to love and men are more able to make war.

As per Indian astrology Mars is a male planet and Venus is a female planet.Mars refers to brothers, land, anger, strength, blood, surgery etc. Venus refers to love, luxury, vehicles, luck etc. etc.

This statement of male and female human characteristics are a remnants and momories of astrology. In Indian Astrology in particular, the position of Venus in the male horoscope is taken to signify the amount of material happiness that a person enjoys and that includes conjugal bliss. The same is determined for the female by studying the position of Mars. Thus Mars is the characterisation of the Male in a females life and Venus, that of the female in a male's life. But the genders of Mars and Venus according the Indian Astrology are all Male only. The linking of the sexes with assumed genders for the planets as indicated in John Gray's book of the same title is due to Western Astrology which draws mainly from Greek sources.