Theory:

Speak gently to the aged one,
     Grieve not the care-worn heart;
The sands of life are nearly run,
     Let such in peace depart!

Speak gently, kindly, to the poor;
     Let no harsh tone be heard;
They have enough they must endure,
     Without an unkind word!

Speak gently to the erring – know,
     They may have toiled in vain;
Perchance unkindness made them so;
     Oh, win them back again!

Speak gently! – He who gave his life
     To bend man’s stubborn will,
When elements were in fierce strife,
     Said to them, ‘Peace, be still.’

Speak gently! – ’tis a little thing
     Dropped in the heart’s deep well;
The good, the joy, which it may bring,
     Eternity shall tell.
Explanation:
  
We should speak soft and politely to the aged people. Generally, older people have gone through enough of their share of happiness and worry. When they are old, their body is worn out, and the mind becomes less active. They need care and attention like any child. Speak to them with care and attention as they left with only some time to live.

image444.jpg
 
Be kind and gentle towards the poor people. They don't enjoy a luxurious life and will be suffering to get food, money, and shelter, so speak to them in a tone that is not rude and don't use rough and unkind words. They have to go through enough problems in their life to earn a living and to feed their families. So, be kind to them.

image555.jpg
 
Speak gently to the prisoners who have made several mistakes in their lives. Maybe they would have become bad due to the unkindness shown to them. The wise words can win their hearts and make them a better person.

Speak gently to god. He always helped man when needed. He gave up his life for the man's stubborn will.  He made sure to be peace when all the elements on earth are in a battle against each other. So, speak to the god with the utmost softness in prayer.

The poet compares our hearts to a deep well. He says talk to yourself so gently that happiness and joy prevails, and to every man ever after.
 
Meaning of difficult words:
 
Numbers
Word
Meanings
1.
EndureSuffer patiently.
2.
Perchance By any chance.
3.
Toiled Work extremely hard.
4.
StrifeConflict.
5.
Stubborn Persistent.
6.
Eternity Life after death.
Reference:
State Council of Educational Research and Training (2019). Term-1 English Standard-7. Your Space by David Bates (pp. 70-72). Published by the Tamil Nadu Textbook and Educational Services Corporation.