Swami Sivananda: "This sacred monosyllable is thus the means of liberation from the bonds of matter and leads one stage by stage to the highest level of bliss. That is why so much importance is attached to it, and why every mantra commences with it. The concentrated essence of Hinduism is manifest in this great monosyllable. It is suitable for the lowest as well as the highest and most advanced intellect, for the celibate as well as the Sanyasin.
"One may raise the question as to why women are prohibited from uttering this mantra. Women are highly emotional and their intellect cannot grasp subtle truths. Further, most Hindu women marry; they do not remain single. The scriptures maintain that the merits of the husband are divided equally between himself and his wife, but his sins do not affect her. Thus, the scriptures have given her a high place. She can attain salvation without any difficulty simply by following her husband. So, these difficult practices are not prescribed for her. Nevertheless, if a woman has a highly developed intellect, she may also take up such practices. She can also repeat the Pranava. An example of such a woman was Chudalai. The prohibition is only for an ordinary woman who benefits from her husband's merit.
"Om is your real birthright. It is the property and spiritual heritage of all people throughout the world. It is the word of power. When chanted with faith and rhythm, it fills one with spiritual strength, new vigor and energy. It brings inspiration and intuition and elevates the mind to spiritual heights of ineffable splendor and glory. Om is your spiritual food and tonic. It is filled with divine potency. It is your constant companion and savior. Meditate on Om regularly. Live in Om. Inhale and exhale Om. Rest peacefully in Om. Take shelter in Om. May Om guide and protect you!"
(pgs. 225-226, Science of Yoga, Vol.5)