It is very difficult to say where concentration ends and meditation begins. Meditation follows concentration. Purify the mind first through the practice of Yama and Niyama. Then take to the practice of Dharana. Concentration without purity is of no use.
Concentration is steadfastness of mind. If you remove all causes of distraction, your power of concentration will increase. A true Brahmachari who has preserved his Virya will have powerful concentration. Attention plays a prominent part in concentration. He who has developed his power of attention will have good concentration. You should be able to visualise very clearly the object of concentration even in its absence. You must call up the mental picture in a moment's notice. If you have good practice in concentration you can do this without difficulty. He who has gained success in Pratyahara (abstraction) by withdrawing the Indriyas from the various objects will have good concentration. You will have to march in the spiritual path step by step, stage by stage. Lay the foundation of Yama (right conduct), Niyama, Asana (posture), Pranayama and Pratyahara to start with. The superstructure of Dharana (concentration), Dhyana (meditation), and Samadhi will be successful then only.
Asana is Bahiranga Sadhana (external); Dhyana is Antaranga Sadhana (internal). When compared with Dhyana and Samadhi, even Dharana is Bahiranga Sadhana. He who has steady Asana and has purified Yoga-Nadis and the Pranamaya Kosha (vital sheath) through Pranayama will be able to concentrate easily. You can concentrate internally on any of the seven plexus or Chakras or centres of spiritual energy viz., Muladhara, Svadhishthana, Manipura, Anahata, Vishuddha, Ajna and Sahasrara, or on the tip of the nose, or on the tip of the tongue or externally on the picture of any Devata, Hari, Hara, Krishna or Devi. You can concentrate on the 'tik-tik' sound of a watch or on the flame of a candle, or on a black point of a wall, or on a pencil or rose flower or any pleasing object. This is concrete concentration (Sthoola). There can be no concentration without something upon which the mind may rest. The mind can be fixed easily on a pleasing object such as jasmine flower, mango or orange or a loving friend. It is difficult to fix the mind in the beginning on any object which it dislikes such as faecal matter, cobra, enemy, ugly face, etc. Practise concentration till the mind is well established in the object of concentration. When the mind runs away from the object of concentration, bring it back again and again to the object. Lord Krishna says in the Gita: "Yato yato nischarati manas-chanchalam-asthiram, Tatastato niyamyaitad-atmanyeva vasam nayet-As often as the wavering and unsteady mind goes forth, so often reining it in, let him bring it under the control of the Self."
If you want to increase your power of concentration, you will have to reduce your worldly activities (Vyavahara-Kshaya). You will have to observe Mouna (vow of silence) also for two hours daily. A man whose mind is filled with passion and all sorts of fantastic desires can hardly concentrate on any object even for a second. His mind will be jumping like a balloon. Regulate and master the breath. Subdue the senses and fix the mind on any pleasing object. Associate the ideas of holiness and purity with the object.
You can concentrate on the space between the two eyebrows (Trikuti). You can concentrate on the mystic sounds (Anahata Dhvani) that you hear from your right ear. You can concentrate on 'Om' picture. The picture of Lord Krishna with flute in hand and the picture of Lord Vishnu with conch, discus, mace and lotus are very good for concentration. You can concentrate on the picture of your Guru or any saint. Vedantins try to fix the mind on Atman, the Inner Self. This is their Dharana.
Dharana is the Sixth stage or limb of Ashtanga Yoga or Raja Yoga of Patanjali Maharshi. In Dharana you will have only one Vritti or wave in the mind-lake. The mind assumes the form of only one object. All other operations of the mind are suspended or stopped. He who can practise real concentration for half or one hour will have tremendous psychic powers. His will also will be very powerful.
When Hatha Yogis concentrate their minds on Shadadhara or the six supports (the Shat-Chakras), they concentrate their minds on the respective presiding Devatas also, viz., Ganesha, Brahma, Vishnu, Rudra, Isvara and Sadasiva. Control the breath through Pranayama. Subdue the Indriyas through Pratyahara. And then fix the mind either on Saguna or Nirguna Brahman. According to the Hatha Yogic School, a Yogi who can suspend his breath by Kumbhaka for 20 minutes can have very good Dharana. He will have a very tranquil mind. Pranayama steadies the mind, removes Vikshepa (distraction) and increases the power of concentration. Those who practise Khechari Mudra by cutting the frenum lingua and lengthening the tongue and fixing it in the hole beyond the palate by taking upwards, will have good Dharana.
Those who can practise concentration evolve quickly. They can do any work with scientific accuracy and great efficiency. What others do in six hours can be done by one who has concentration within half an hour. What others can read in six hours, can be read by one who has concentration within half an hour. Concentration purifies and calms the surging emotions, strengthens the current of thought and clarifies the ideas. Concentration helps a man in his material progress also. He will have a very good outturn of work in his office or business-house. What was cloudy and hazy before becomes clear and definite. What was difficult before becomes easy now and what was complex, bewildering and confusing before comes easily within the mental grasp. You can achieve anything through concentration. Nothing is impossible to a man who practises regular concentration. It is very difficult to practise concentration when one is hungry and when one is suffering from an acute disease. He who practises concentration will possess very good health and very clear mental vision.
Retire into a quiet room; sit in Padmasana. Close your eyes. See what happens when you concentrate on an apple. You may think of its colour, shape, size and its different parts such as skin, pulp, seeds, etc. You may think of the places (Australia or Kashmir) wherefrom it is imported. You may think of its acidic or sweet taste and its effects on the digestive system and blood. Through law of association, ideas of some other fruits also may try to enter. The mind may entertain some other extraneous ideas. It may begin to wander about. It may think of meeting a friend at the railway station at 4 p.m. It may think of purchasing a towel or a tin of tea and biscuits. It may ponder over some unpleasant happening that occurred the previous day. You must try to have a definite line of thought. There must not be any break in the line of thinking. You must not allow other thoughts which are not connected with the object on hand to enter. You will have to struggle hard to get success in this direction. The mind will try its level best to run in the old grooves and take its old familiar road or old beaten path. The attempt is somewhat like going uphill. You will rejoice when you get even some success in concentration. Just as laws of gravitation, cohesion, etc., operate in the physical plane, so also definite laws of thought, such as law of continuity, etc., operate in the mental plane or thought-world. Those who practise concentration should thoroughly understand these laws. When the mind thinks of an object, it may think of its qualities and its parts also. When it thinks of a cause, it may think of its effect also.
If you read with concentration the Bhagavad-Gita, the Ramayana, or the 11th Skandha of Bhagavata several times you will get new ideas each time. Through concentration you will get penetrative insight. Subtle esoteric meanings will flash out in the field of mental consciousness. You will understand the inner depths of philosophical significance. When you concentrate on any object do not wrestle with the mind. Avoid tension anywhere in the body or mind. Think gently of the object in a continuous manner. Do not allow the mind to wander away.
If emotions disturb you during concentration, do not mind them. They will pass away soon. If you try to drive them, you will have to tax your will-force. Have an indifferent attitude. The Vedantin uses the formulae: "I don't care. Get out. I am Sakshi (witness of the mental modifications)," to drive the emotions. The Bhakta simply prays and help comes from God.
Train the mind in concentration on various subjects, gross and subtle, and of various sizes, medium and big. In course of time a strong habit of concentration will be formed. The moment you sit for concentration the mood will come at once quite easily. When you read a book, you must read it with concentration. There is no use skipping over the pages in a hurried manner. Read one page in the Gita. Close the book. Concentrate on what you have read. Find out parallel lines in the Mahabharata, the Upanishads and the Bhagavata. Compare and contrast.
For a neophyte, the practice of concentration is disgusting and tiring in the beginning. He has to cut new grooves in the mind and brain. After some months, he will get interest in concentration. He will enjoy a new kind of happiness, the Concentration-Ananda. He will become restless if he fails to enjoy this new kind of happiness even for one day. Concentration is the only way to get rid of the worldly miseries and tribulations. Your only duty is to practise concentration. You have taken this physical body to practise concentration and through concentration to realise the Self. Charity, Rajasuya Yajna are nothing when compared to concentration. They are playthings only.
Through Vairagya, Pratyahara and practice of concentration, the dissipated rays of wandering mind are slowly collected. Through steady practice it is rendered one-pointed. How happy and strong is that Yogi, who has one-pointed mind! He can turn out voluminous work in the twinkling of an eye.
Those who practise concentration off and on will have only occasionally a steady mind. Sometimes the mind will begin to wander and will be quite unfit for application. You must have a mind that will obey you at all times sincerely and carry out all your commands in the best possible manner at any time. Steady and systematic practice of Raja Yoga will make the mind very obedient and faithful.
There are five Yoga-Bhumikas or stages of the mind viz., Kshipta (distracted), Mudha (dull), Vikshipta (slightly tossing), Ekagra (one-pointed), Niruddha (controlled or well-restrained). By gradual and well-regulated practice of concentration daily, the rays of the wandering mind are collected. It becomes one-pointed. Eventually it is curbed properly. It comes under proper control.
If the aspirant pursues what is not fitting, his progress is painful and sluggish. He who pursues the right path gets easy progress and quick intuition. He who has no past conditions or Spiritual Samskaras of previous birth makes painful progress. One who has spiritual Samskaras makes easy progress. To one whose nature is actually corrupt and whose controlling faculties are weak, progress is painful and intuition is sluggish. But to one of keen controlling faculties, progress is rapid and intuition is quick. In one overcome by ignorance intuition is sluggish; in one not so overcome, intuition is rapid.