The word 'love' in English has many meanings. These include a simple liking for something ('I love chocolate'), sex, romance, an expansive and universal goodwill, or even a transcendental feeling of unity. It can even mean 'nothing' (zero score in whist or tennis) - from the phrase 'play for love', meaning you don't care if you have scored or not (Michael Quinion gives this as the derivation of 'love' meaning zero, rather than the often-quoted French l'oeuf - egg).
It helps to separate out these meanings by looking at the ancient Greeks, who had at least four words for love: eros originally meant an intense desire for beauty (Plato), but came to be used to mean a 'desire for something', and is now used almost exclusively when that 'something' is sexual (hence the word 'erotic'); storge was family love, the feeling of belonging to small group; philia was love for friends, and is best translated by our word 'friendship'.
The fourth word is agape, which in classical Greek was rarely used, and even then in several different meanings. The writers of the New Testament adopted it (probably because it was rare) as the word to use for the Christian ideal of love, loving both the universal (loving God 'with all your heart, and with all your soul, and with all your might') as well as loving others without necessarily hoping for a trade-off of getting something in return ('love your enemies..'). When St Jerome translated the Greek New Testament into Latin in the 4th century, he translated agape into the Latin caritas or charitas, from which our word 'charity' is derived.
I have to admit that the word 'love', in its most inclusive agape-like sense, strikes a resonance with me. Sometimes it annoys me as well, when it is used in a cloying artificial way, like a palliative - the uncritical answer to everything. But used in the appropriate way, I love it (excuse the pun). I find it hard to say what this appropriate way is. But for me, love in this sense must embrace the universal, and go beyond any particular; it must be expansive and inclusive; it must be warm and passionate; it must be freely given, without any desire for reciprocal benefits; and freely accepted, without any guilt or embarrassment.
All these facets of love are, for me, contained in the four Buddhist Brahma Viharas (a brahma in Buddhism is a pure or noble being, not to be confused with the Hindu god Brahma; and vihara means home or abode):
-- metta: translated usually as loving kindness or goodwill displayed to all.
-- karuna: compassion or mercy towards those suffering.
-- mudita: sympathetic joy, happiness at the good fortune of others.
-- upekkha: equanimity, accepting others as they are.
On this site, I am often critical of the Buddhist Commentaries. Here is a summary that I like of these four qualities from one of the Commentaries (the
Visuddhimagga): metta embraces all beings; karuna embraces all who suffer; mudita embraces all who prosper; upekkha embraces the good, bad, loved and unloved, pleasant and unpleasant (quoted in BuddhaMind, slightly edited).
Much is written about these four qualities, the most well-known of which is metta, which is sometimes used as a summary of the whole group. They are also used in different ways; often as a 'meditation' (brahma vihara bhavana), where one mentally tries to radiate these qualities to ever-widening circles of beings (starting with yourself). I don't find this style of meditation helpful for me; I just use these four brahma viharas as a summary and a teasing out of what I mean by 'love'.
I think one thing is very important though: my 'love' must start with myself. Most styles of brahma vihara bhavana, for instance, begin by applying metta and the rest to oneself first, before attempting to radiate them out to anyone else. The Greeks, in their use of agape, thought that you needed to start by applying it to yourself (at least Aristotle did). The New Testament suggests this too ('love your neighbor as yourself'), although St Augustine disagreed (he thought it was egotistic).
So to summarise:
-- I cannot define 'love', but in its widest and most inclusive sense I believe it lies at the heart of any true understanding of myself and the universe I live in, and I need to feel it more.
-- Whatever Love (with an upper case 'L') is, the only place to begin to understand it is within myself.
-- Whatever Love (with an upper case 'L') is, it is not a philosophy, or set of beliefs, that I somehow have to psych myself up into accepting; nor is it a way of acting towads others that I can pretend, or force myself to do. I cannot 'do' Love; I can only experience it.