If we allow our compassion to remain only inside of ourselves, our compassion will become powerless, without a function. It would become like a vase that despite having the ability to carry water had been placed high upon a shelf and never used.
To expand our compassion we can apply our imagination to everyday’s situations. Sometimes when the wind blows I imagine that my compassion mixes with the wind and is carried in every direction to touch all sentient beings. Sometimes when I see beautiful clouds in the sky I imagine that they carry my compassion and that all beings over whom the clouds hover also experience the feeling of compassion. We can also do contemplation involving our five sense faculties. For example, we continually have objects in our visual field. Having first giving rise to compassion mentally we can then spread that compassion to any sentient being who appears before our eyes and imagine that they experience all of our compassion, love and joy.