Self-realization and purity of mind 
The
 scriptures and great teachers of all paths
 have spoken extensively  about the importance of purity 
for those who want to attain Self-realization eternal freedom and  bliss.
 I expose here a selection of significant
 quotes. 
 
‘
 But whoso is devoid of a discriminating intellect, possessed of an 
unrestrained mind and is ever impure, does not attain that goal, but 
goes to samsara.’
‘
 But whoso is possessed of a discriminating intellect and a restrained 
mind, and is ever pure, attains that goal from which he is not born 
again.’
Katha Upanishad
‘ Serenity of mind, good-heartedness, purity of nature, self-control—this is called mental austerity.’
Bhagavad Gita
‘Blessed are the pure in heart, for they shall see God.’
Jesus Christ
‘While
 your minds and hearts are impure, how can God live in your hearts? The 
water to clean the heart is the name of God. So, teach everyone to 
repeat the name of God - everywhere.’
 Haidakhan Babaji
‘To have a heart as pure as crystal, a mind as luminous as the sun, a soul as vast as the universe,  a spirit as powerful as God and one with God.’
Aivanhov
‘On
 the contrary, these are only certain indications necessary at a 
particular stage; they are chiefly important for purification, which is 
the first part of the Yoga. After the shuddhi is complete one has to 
perfect the mukti, to get liberation, a thing easy after shuddhi, 
impossible before it.’ 
Sri Aurobindo
‘But
 in the pure mind that has been rendered subtle and unmoving by the 
meditation described above, the Self bliss (i.e., Brahman) will become 
manifest. As without mind there cannot be experience, it is possible for
 the purified mind endowed with the extremely subtle mode (vritti) to 
experience the Self-bliss, by remaining in that form (i.e. in the form 
of Brahman). Then, that one’s Self is of the nature of Brahman will be 
clearly experienced.’ 
Sri Ramana Maharshi SELF-ENQUIRY
‘What is the authority for saying that Brahman can be apprehended by the mind and at the same time that it cannot be apprehended by the mind?’ 
‘ It cannot be apprehended by the impure mind but can be apprehended by the pure mind.’
Sri Ramana Maharshi SPIRITUAL INSTRUCTIONS 
‘Good conduct or sat karma purifies the chitta or mind and gives you chitta suddhi. The pure mind attains jnana, which is what is meant by salvation.’
Sri Ramana Maharshi  DAY BY DAY  
‘Clarify your mind, purify your heart, sanctify your life -- this is the quickest way to a change of your world.’
‘The
 main thing is to be free of negative emotions desire, fear etc., the 
'six enemies' of the mind. Once the mind is free of them, the rest will 
come easily. Just as cloth kept in soap water will become clean, so will
 the mind get purified in the stream of pure feelings.’
‘ All that is needed is to purify the mind so that it can realize its identity with the Self’.
Nijargadatta Maharaj I AM THAT
'Another condition [for success in Yoga] is chastity. It is the corner-stone of all practice. Married or unmarried — perfect chastity.'
'Nothing is gained except by sacrifice.... The holiest function of our human
consciousness, the noblest, do not make it unclean! Do not degrade it to the level of the brutes.... Make yourselves decent men! ... Be chaste and pure! ...'
Swami Vivekananda 
"God is realized as soon as the mind becomes free from attachment. Whatever appears in the Pure Mind is the voice of God. That which is Pure Mind is also Pure Buddhi; that, again, is Pure Ātman, because there is nothing pure but God. But in order to realize God one must go beyond dharma and adharma." 
"God cannot be known by the sense-organs or by this mind; but He can be known by the pure mind, the mind that is free from worldiy desires."
"God can be seen. He can be seen through the pure mind and the pure intelligence. Through attachment to 'woman and gold' the mind becomes impure." 
"He is unknowable by the mind engrossed in worldliness. One cannot attain God if one has even a trace of attachment to 'woman and gold'.
 "But He is knowable by the pure mind and the pure intelligence―the mind and intelligence that have not the slightest trace of attachment. 
'Pure Mind, Pure Intelligence, Pure Ātman, are one and the same thing." 
Parmahansa Ramakrishna  
 ‘Therefore it was also said that the sole necessity for Self-realisation is purity of mind.’ 
Book TRIPURA RAHASYA
‘
 Therefore the mind is the only cause that brings about man’s bondage or
 Liberation: when tainted by the effects of Rajas it leads to bondage, 
and when pure and divested of the Rajas and Tamas elements it conduces 
to Liberation.‘
" Therefore the seeker after Liberation must carefully purify the mind. 
When this is purified, Liberation is as easy of access as a fruit on the
 palm of one’s hand.’
‘Attaining purity through a preponderance of discrimination and renunciation, the mind makes for Liberation. Hence the wise seeker after Liberation must first strengthen these two.’
‘The man of pure mind realises the Supreme Self, and by this alone Samsara with its root is destroyed.’
‘The
 truth of the Paramatman is extremely subtle, and cannot be reached by 
the gross outgoing tendency of the mind. It is only accessible to noble 
souls with perfectly pure minds, by means of Samadhi brought on by an 
extraordinary fineness of the mental state’.
Adi Sankaracharya VIVEKACHUDAMANI 
‘The purity of the seeker’s mind is the sole means for realization.’
‘By repeated practices in several rebirths his mind becomes pure and turns away from sense enjoyments to receive the highest teaching of the nondual Reality.’
Book ADVAITA BODHA DEEPIKA OR THE LAMP OF NON-DUAL KNOWLEDGE
 ‘From
 mental purity arises purity of the inner nature, cheerfulness, 
one-pointedness, control of the senses, and fitness for the vision of 
the self.’)
Patanjali  YOGA SUTRAS
‘All the techniques of Yoga require perfect ethical and moral purity. This purity is the foundation of Yogic life.’
 Swami Chitananda THUS SPEAKS
‘No
 one should seek to do meditation without purity of heart. One is not to
 enter the path unless the preconditions are fulfilled.’
Swami Krishnananda YOGA SYSTEM 
‘ Only Yogis of pure mind can cross this river and enjoy the highest Bliss.’
Swami Sivananda HOW TO GET VAIRAGYA 
‘The
 pure divine qualities are conducive to peace and liberation and the 
undivine qualities lead to bondage. Purity, good conduct and truth are 
indispensable to spiritual progress and even to an honourable life 
here.’
Commentary of Swami Sivananda on BHAGAVAD GITA 
 ‘Even
 so it takes a long time for igniting the fire of knowledge for a man 
whose heart is impure. But an aspirant with great purity of heart gets 
knowledge of the Self within the twinkling of an eye, within the time 
taken to squeeze a flower by the fingers.’
Swami Sivananda EASY STEPS TO YOGA
 ‘The
 way to liberation or freedom or perfect happiness and peace is through 
perfect purity of mind and heart, of every act, of character and life, 
through self-restraint and control of mind, and through regular 
meditation on the pure self-luminous, indivisible, all-pervading Self or
 Atman.’
Swami Sivananda ESSENCE OF YOGA                                                                                                                                                              
‘Serve,
 Love, Give, Purify, Meditate, Realise. Be good; do good. Be kind; be 
compassionate. Practice non-injury, truth and purity. This is the 
foundation of Yoga and Vedanta.’
Swami Sivananda INSPIRING THOUGHTS
Peace  love  harmony