A traveller on a dusty road 
Strewed acorns on the lea; 
And one took root and sprouted up, 
And grew into a tree. 
Love sought its shade at evening-time, 
To breathe its early vows; 
And Age was pleased, in heats of noon, 
To bask beneath its boughs. 
The dormouse loved its dangling twigs, 
The birds sweet music bore-- 
It stood a glory in its place, 
A blessing evermore. 
 
A little spring had lost its way 
Amid the grass and fern; 
A passing stranger scooped a well 
Where weary men might turn; 
He walled it in, and hung with care 
A ladle at the brink; 
He thought not of the deed he did, 
But judged that Toil might drink. 
He passed again; and lo! the well, 
By summer never dried, 
Had cooled ten thousand parched tongues. 
And saved a life beside. 
 
A dreamer dropped a random thought; 
'Twas old, and yet 'twas new; 
A simple fancy of the brain,  
But strong in being true. 
It shone upon a genial mind, 
And, lo! its light became 
A lamp of life, a beacon ray, 
A monitory flame: 
The thought was small; its issue great; 
A watch-fire on the hill, 
It sheds its radiance far adown, 
And cheers the valley still. 
 
A nameless man, amid the crowd 
That thronged the daily mart, 
Let fall a word of hope and love, 
Unstudied from the heart,-- 
It raised a brother from the dust, 
It saved a soul from death. 
O germ! O fount! O word of love! 
O thought at random cast! 
Ye were but little at the first, 
But mighty at the last.
Charles Mackay
http://www.poemhunter.com/poem/little-and-great/