Svadhyaya is study of scriptures and books written by realised sages. It is one of the limbs of niyama (discipline) in Raja Yoga. Svadhyaya is also enquiry of the nature of Atman (Self), or "Who am I?". It is recitation of mantras (sacred formulas) also. Svadhyaya is indirect satsanga, when you cannot get positive satsanga of mahatmas (company of holy ones). Svadhyaya clears doubts, it strengthens the flickering faith, it induces strong yearning for liberation or aspiration, it gives encouragement and illumination, it places before you a list of saints who trod the path, encountered and removed difficulties, and thus cheers you up with hope and vigour. It fills the mind with satva (purity). It inspires and elevates the mind. It helps concentration and meditation. It cuts new satvic (pure) grooves and makes the mind run in these new grooves.
Svadhyaya is daily study of religious scriptures. It is daily parayana (study) of sacred books. It is the fourth anga (limb) of Raja Yoga niyama. It inspires and elevates the mind to high spiritual altitude. It clears doubts. It weeds out unholy ideas and cuts new spiritual grooves for the mind to move along. It reduces wandering of the mind (vikshepa). It helps concentration. It forms a kind of lower (savikalpa) samadhi (super-consciousness). It serves the purpose of spiritual pasture for the mind to graze upon. When you study the sacred books, you are in tune with the authors who are realised souls; you draw inspiration and become ecstatic.
Japa is the best of all spiritual practices in this modern age. It is the easiest too. Divine name alone will give you all success and bestow the highest spiritual attainments on you. The seeker after truth realises the highest goal of japa or recitation of the Lord's name alone. Have faith in the saving grace of God and in the power of the Lord's name. Repetition of the Lord's name is a sure medicine for the disease of birth and death.
Japa of a mantra can bring the practitioner the realisation of his highest goal, even though he has no knowledge of its meaning. There is an indescribable power in the name of God (the mantra). If you repeat it with concentration on it's meaning, you will attain God-realisation quickly.