Longing is a heartfelt desire to be united with someone or something, or to fulfill some goal or purpose. Longing is always a feeling of simultaneously being so close to something in your heart and yet so far away currently or physically, and the desire to bridge that gap. Longing can be for grosser to subtler objects.
Grosser objects one can have longing for always pertain to physical pleasure. Whether for food, sex, or other pleasures, these base desires are the least about our heart's fulfillment and more about our bodies. Even still you may associate the physical pleasure with some sentimental value of what it means to you which affects why you long for it and not just crave or desire it. One distinction to be made however is that longing is not addiction. Longing is for the most part a healthy state of mind since it always includes your heart in some way, even though you may suffer from not having your longing fulfilled. Addiction is always a negative state of desire that does not fulfill your heart ultimately and always leads to great suffering.
Longing that is more subtle or deeper has to do with emotional pleasures. You may have a longing to see a popular movie, or a play. You may have a longing to do photography or work in whatever job you love. You may have a longing to participate in the marathon or to build a boat, to go to a certain school or to travel to a certain country. These kinds of longings pertain to something your heart is telling you to seek out, something you have emotional investment in because your heart tells you to, and so you desire these things in a heartfelt way. These longings are always healthy, and tell you how to fulfill your life. These are called your calling, or following your heart.
Deeper still is the longing to connect to other people. This may be the longing you have for someone you consider to be your true love, or a longing to see a friend or family member you haven't seen in a long time, like when veterans return from war to see their family for the first time in many months or years. This longing always involves the love we share for each other, and is based solely in that love.
In spiritual practice one type of longing that can develop is the longing to love others. Even strangers on the street walking by can stir in us a deep longing to love them and feel their preciousness. This is an unending and vibrant source of fulfillment and can help to guide our life.
The deepest most subtle longing we can have is for union with the Divine. This is at the basis of our spiritual practice. By knowing the qualities of the Divine, like those of infinite love and infinite wisdom, we can be deeply inspired to be closer to those qualities so that we can become one with the Divine. Through meditation, or prayer, or any other means that includes devotion or invoking our presence to the Divine, we slowly but surely begin to be imbued with some of the qualities of the Divine, like greater love, deep appreciation for the meaning of life, and greater sensitivity and wisdom.
Longing is a beautiful human emotion, one which sings through the pages of the spiritual poets and mystics of history. It is our heart's yearning for its own fruition. May we come to know the longing we may have in our hearts and learn from what it teaches us about how we love and how we may fulfill our life.