Sunlight falling on a flat mirror warms nothing, but gathered by a lens to a single point it burns. ‘Abdu’l-Bahá uses that image for the mind: scattered thoughts achieve no result, and attention concentrated on one thing becomes a force. The same holds for water gathered into a single fountain, for the student of an art who cannot learn it while half attending to something else, and for anyone who wishes truly to serve God. Yet the capacity to focus raises a second question, what deserves it, and here the answer is remembrance: the first thought on waking, the presence of the Almighty known before a prayer begins rather than the birds outside the window, a heart that is not heedless of God for a single moment, in standing and sitting, sleeping and waking. Such attention does not retreat from work; the ploughman’s hands and feet are busy in the field while his heart stays with the Beloved. The Bhagavad Gita’s counsel to bring the wandering mind back, again and again, to the Self describes a kindred discipline with its own account of the goal [1]. Mindfulness also means noticing consequences and learning from yesterday, so that heedlessness does not injure a shared life. The path continues into contemplation and meditation, into composure and serenity, and into the discipline of self-perfection.
So long as the thoughts of an individual are scattered he will achieve no results, but if his thinking be concentrated on a single point wonderful will be the fruits thereof.
One cannot obtain the full force of the sunlight when it is cast on a flat mirror, but once the sun shineth upon a concave mirror, or on a lens that is convex, all its heat will be concentrated on a single point, and that one point will burn the hottest. Thus is it necessary to focus one's thinking on a single point so that it will become an effective force.
(‘Abdu’l-Bahá, 1919-Jul-26, to Elizabeth Herrick -- AB00948)
02
Focus your thoughts on this matter, for this is what is beneficial now. Do not scatter your thoughts. If you scatter your thoughts you will not succeed in any one thing. When water is concentrated in one fountain, the fountain becomes very powerful and gushes forth strongly, but when divided among multiple fountains, none of the fountains gains strength.
(‘Abdu’l-Bahá, 1911-Apr-24, to Ali-Kuli Khan -- AB12128)
03
When man wishes to accomplish something, he must give himself entirely to that thing. For instance, if one desires to learn art, he must concentrate all his faculties and mind upon it; he cannot do that and something else at the same time. So when a man wishes truly to serve God, he must concentrate all his mind upon this service and think of nothing else whatever.
When a soul rises in the morning from sleep, before everything else he must commemorate the name of God, in order that he may obtain spirituality and illumination....
(‘Abdu’l-Bahá, 1914-Mar-05, to Elizabeth Bowen -- AB10943)
The available source contains an omission or incomplete wording; sentence boundaries need review.
05
When you pray you must not think of your aching body, nor of the birds outside the window, nor of the cracks in the wall! When you wish to pray you must first know that you are standing in the presence of the Almighty!
O Rahim! Remember God, thy Lord, in thy heart and forget Him not, and be not of the heedless ones.
(Bahá’u’lláh, 1290 [1873] or earlier, to Rida et al -- BH05299)
07
And the greatest spiritual discipline in this regard is that thy heart not be heedless of God's remembrance for a single moment.
(The Báb, Letter to Mulla Hasan Bajistani, 1261 [1844-1845] -- BB00580)
08
Take no rest except in remembrance of God. This is what the Dove of the Spirit counseleth you that haply ye may be guided by the guidance of God, and may conduct yourselves upon the earth in accordance with His will. This is better for you than all that hath been and will be. And take no breath except in remembrance of the Beloved, if ye would be guided by this counsel.
God willing, thou shalt be mentioned among the people through the name of Truth and be accounted among the servants of the divine Cause, in such wise that at all times thou shalt be occupied with the remembrance of the All-Merciful.
(Bahá’u’lláh, 1290 [1873] or earlier, to Mulla Abdullah Fadil Zarqani (Rafi) -- BH06107)
11
When you are plowing the ground or sowing the seeds or reaping the harvest let all your thoughts and subconscious thinking be of God.
(‘Abdu’l-Bahá, Words spoken on 1914-May-17 in Tiberias -- ABU2111)
12
The body of man is created for this world, but his heart is made for the habitation of the Holy Spirit… When you are plowing the ground or sowing the seeds or reaping the harvest let all your thoughts and sub-conscious thinking be of God. Your hands and feet will be working but your heart must be attached to the Almighty.
(‘Abdu’l-Bahá, Words spoken on 1914-May-17 in Tiberias -- ABU3244)
The available source contains an omission or incomplete wording; sentence boundaries need review.
13
Think day and night how thou mayest render some service at the Sacred Threshold.
(Bahá’u’lláh, 1305-10-24 [1888-Jul-4], to mother of Afnan -- BH07432)
15
Since one has no encompassing knowledge of the consequences of affairs, therefore one must always take the path of mindfulness and wisdom, and learn lessons from the past for the future.
(‘Abdu’l-Bahá, Words spoken on 1913-Mar-26 in Paris -- ABU0912)
16
These sad events which are transpiring in the East are the results of thoughtlessness. Thoughtlessness is the worst calamity of the human race.
(‘Abdu’l-Bahá, Words to the Master's entourage, spoken at Baltimore Hotel on 1913-May-06 -- ABU1060)
17
O God! Awaken us from the deep slumber of negligence! Suffer us to become mindful and aware!
(‘Abdu’l-Bahá, Public address at Theosophical Society given on 1913-Apr-12 -- ABU2174)
18
Then remember Him at all times, for by His remembrance the sleeping servants of God shall be awakened.