I believe the following to be the ULTIMATE meaning:
When you're weary
Feeling small
When tears are in your eyes
I will dry them all
I'm on your side
Typical hardship of mundane existence. Feeling lost. Being aware of the lower self only. Not realizing that we have a dormant Higher Self or Divine spark ("Savior") which is awaiting our realization. Once truly realized, this Higher Self will "take away all tears" because the divine spark within us is "for us" and not against us. This Light within is "on our side" because it is the Light of the universe to which we all belong. No more seeing ourselves as separate entities. We are all ONE once this inner Light is turned on, though in essence we have always been one, but just blinded to this knowledge by our lower self/EGO.
When times get rough
And friends just can't be found
Like a bridge over troubled water
I will lay me down
Like a bridge over troubled water
I will lay me down
The Bridge is the "highway" (recorded in many religious metaphors) that carries us from this world of woe to Higher consciousness and realization. This "Bridge" is the ONLY "way" to true Life. Metaphorically speaking, this Bridge, Highway or "Savior" "lays itself down" for us (on our behalf) that we may pass over it and escape the hell of this lower mundane life of suffering which is due to our spiritual blindness.
When you're down and out
When you're on the street
When evening falls so hard
I will comfort you
I'll take your part
We all experience different and various degrees of suffering. Once we begin to truly realize that we have been imprisoned to our lower Ego, the Bridge will appear and we will be comforted from this time on... forever. Our inner Light or Higher Self will now "take our part" over these earthly sorrows... and "dry away all tears".
When darkness comes
And pain is all around
Like a bridge over troubled water
I will lay me down
Like a bridge over troubled water
I will lay me down
Trails and tribulations can become intense. Unenlightened humanity is like the turbulent sea that cannot rest. This Bridge to peace is always dwelling just "above" these troubled waters, in the person of one's "Higher" Consciousness... always waiting for us to cross.
Sail on Silver Girl,
Sail on by
Once we realize the reality of this Bridge, our lives become "smooth sailing" from here on out. Most definitely "smooth sailing" as compared to our lives as "troubled waters". Metaphorically speaking, all people who are on this bridge are known as "virgins" (in the main religions of the world) ... "virgins" because they have a new life altogether now and are "pure" because of their Higher understanding. They now realize that they are not separate beings, but rather eternal consciousness ... therefore they are not "defiled" with the lower-thinking limitations of the Ego. These "silver" virgins (girls) have escaped the troubled waters and are now reflecting divine inner light from their Higher Self... as the moon reflects its light from the source.
Your time has come to shine
All your dreams are on their way
See how they shine
It is finally their time to "shine". They are now radiant beings who realize their true connection to the universe. Their "dreams" are manifesting now... not the desirous, materialistic "dreams" of the ego, but rather "dreams" of true peace and rest and joy which can only be found by crossing the Bridge. See how they shine! To shine is to ascend or bloom into Higher radiant consciousness.
If you need a friend
I'm sailing right behind
This "Bridge" is also your "friend". Your Higher Self has always been and always will be your "Friend". It will never leave you nor forsake you. Therefore, when you need a "friend" your inner LIGHT is always there... always traveling with you.
Like a bridge over troubled water
I will ease your mind
Like a bridge over troubled water
I will ease your mind
The lower earth-bound "mind" is the source of all sorrow. This is standard knowledge among the ancient wisdom writings of the world. This is what all main religions of the world metaphorically point to. This is the core teaching of them all. When we realize our Higher Self (Bridge), we finally become "awakened" or "liberated" or "enlightened" or "saved". Our "minds" have been "eased" to say the least!