Buddha dhamma is child's-play

From this, comes that. Buddha dhamma is child's-play. This is a controversial thing to say. Here is what is meant by it. When a child takes its first steps, it does so entirely with faith (saddha). Having decided for itself with its own wisdom (panna) to move away from the stress (dukkha) and helplessness of birth (jati), the child becomes determined to make an effort (viriya) to move towards its liberation (vimutti). Watching the concentration (samadhi) in its eyes and careful anticipation in its every movement is to see mindfulness (sati) in its purest form. The child falls, tries again, confidence increases. Joy (pamojja) at accomplishment, rapture (piti) at the sudden rush of new physical sensations (rupavedanakhanda), rapidly flow into alternating states of tranquillity (passaddhi) and happiness (sukkha) that are quite contagious for all nearby. This is easily understood as ordinary, mundane happiness. It is worth considering that sukha, the word for happiness in Pali, (the antonym of the “contemptible emptiness,” “difficult to endure” of stressful dukkha), means literally a “pleasant burden,” “easily endured” as an “enjoyable emptiness.” This seems to connect it etymologically not only with sukere, the Indo-European/Arabic root for sweet sugar, but also with the Latin succurrere, the root for the English word succour, meaning to help or give sweet relief. So it is that the smallest step on a child's journey gives sweet, if limited and transient relief when it is accomplished. So it is also with with the causal patterns of language and experience.

From this, comes that. The deepest dhamma knowledge at the very heart of the Buddha's gift to the world is the conditional causal patterning of “dependent arising” (paticcasamupadda). The understanding of the Four Noble truths, the Eightfold path, the very point of the Buddha's entire teaching, relies on grasping the causal patterning of experience. Transience (annicca), suffering (dukkha), and non-self (annatta) could perhaps be argued against as mere intellectual views, without them being given some solid grounding in a causal sequence able to demonstrate the rising and falling of samsaric suffering. More importantly, it helps to prove that no matter how contemptible and overwhelming the affliction of suffering (dukkha) seems, “dependent arising” (paticcasamupadda) means it is merely passing by; not a continuous, permanent reality but an empty phenomenon, a hollow chimera, a clouded delusion, a causally dependent chain of events, conventionally described as “beginning” with unknowing ignorance (avijja) and “ending” with the stress of suffering (dukkha). 
More important for the potential happiness of all beings in the world is the exposition of the reverse order, moving from suffering to transcendence. [You can listen here as the Upanisa Sutta skilfully draws out the liberating nature of this transcendent order in the Tathagata's own words. You can read Bhikkhu Bodhi's brilliant exposition of this sutta.]

From this, comes that. Just as the child finds its feet, so it is the seeker after liberation finds that with a little effort, a little confidence, a little concentration, and a little mindfulness, they are not trapped in an infant state, reduced to tears and struggle, but fully able to grasp the upright position. We have all successfully faced the varied trials of childhood accomplishment. What is so different with practising on a regular basis as an adult a little samatha and anapana meditation? You will find, right there in your heart/mind (citta), there is always a little childlike samadhi, a little smiling state of vipassana sukha waiting to be aroused and tasted. May all beings be happy.